Rebuilt Set

A set has to be rebuilt. Sometimes this is due to it having been taken down between movies, and the designers take the opportunity to revamp the set in the meantime. Other times its because they want to do something nostalgic, and this often involves rebuilding a set from an earlier version of the franchise.

Common to film sequels, but also a horribly common problem in videogames, since source files are so poorly kept track of. In the case of sets that have been changed, sometimes the producers choose to Trash the Set to explain why they've been changed.

Film - Animated

 * After a fire at their warehouse, almost every Aardman Animation model was destroyed, forcing them to remake pretty much every character and set used in Wallace and Gromit before making A Matter of Loaf and Death.

Film - Live Action

 * Serenity was rebuilt for the movie of the same name.
 * They had to recreate the miniatures from 2001: A Space Odyssey for 2010: The Year We Make Contact because the originals were destroyed after filming 2001 to make sure they wouldn't be reused in other movies.
 * On a related problem, they had tremendous difficulty recreating the 'old man' makeup for the old man version of Dave, as the only surviving images of the makeup were the ones in the original film. Success was confirmed when a passerby on the lot recognized the makeup.
 * Mel Brooks' Young Frankenstein rebuilt sets from the classic 1930s movies, often using original props.
 * Star Wars had to do this for the movie prequel's Tatooine sets, since they were actually built in real-life deserts and had been swallowed up by sand over the decades.
 * An example of the revamp the set version: the Millennium Falcon interior sets were outfitted with more flashing lights and other detailing between A New Hope and The Empire Strikes Back.
 * The Harry Potter filmmakers were Genre Savvy. After Order of the Phoenix, the Ministry of Magic set was taken apart and put into storage so that they could easily put it back together again for Deathly Hallows Part 1.
 * Some places originally shot on location were later reproduced as sets at Leavesden Studios. For example, Privet Drive was a real street on the first movie, but a backlot reproduction was used from the second movie onward. The hospital wing was Oxford Divinity School in the first movie, but it became a set in the second film. Amusingly, Oxford Divinity School later appeared as a different room in the fourth movie. In a weird example, Snape's classroom was filmed in the Lacock Abbey sacristy in the first film, but later his classroom became a set which did not even remotely look like the same room. It appears they took the Snape's office set from the second movie and revamped it into his classroom for the fifth movie (the classroom does not appear onscreen between the first and fifth movies).
 * A grassy courtyard in Hogwarts was filmed in the cloister of Durham Cathedral for the first two movies. Then in the fourth film, a courtyard at Oxford's Magdalen College was used to depict the same location. Finally, the sixth movie reproduced the courtyard as a Leavesden set.
 * The Chamber of Secrets set was not saved after the filming of Harry Potter and the Chamber of Secrets. When the Chamber had to reappear in Hallows: Part 2, they filmed the actors in front of a green screen and recreated the Chamber as a CGI set rather than rebuilding it for real. This makes a certain amount of sense, seeing how the Chamber was a very large set and the scene featuring it in Hallows was pretty brief.
 * Similar to the 2010 example, the CGI spiders in the second film were created by a visual effect house which had closed down by the time the last film was in production. Since the spiders were due to reappear and the original CGI models were lost, they had to be recreated using footage from the second film as reference.

Live Action TV

 * The later Star Trek series have rebuilt or partially rebuilt sets from the original Star Trek from time to time ("Relics" of Star Trek: The Next Generation, "Trials and Tribble-ations" of Star Trek: Deep Space Nine and "In a Mirror, Darkly" of Star Trek: Enterprise).
 * The TOS bridge set in "Relics" was built partly from original props and on the original stage, but they rented a replica of the captain's chair from a fan. Kirk's original chair went missing at some point, apparently.
 * A "they took the opportunity to revamp the set" example occurs in Star Trek Generations, where during the short hiatus between the TNG television series and the movie, the designers significantly altered the 1701-D bridge, adding new workstations and placing steps beneath the Captain's chair (symbolically raising him above the two chairs either side of him).
 * Some Next Generation sets were rebuilt for the Enterprise finale "These Are The Voyages..." Only a small part of Ten Forward was rebuilt with Stock Footage being used for an Establishing Shot of the room. The only set which did not have to be rebuilt from scratch was the observation lounge, which had since been modified to become the observation lounge of the Enterprise-E, so they just had to modify it back.
 * The Excelsior bridge from Star Trek VI: The Undiscovered Country was rebuilt for the Star Trek: Voyager episode "Flashback". The original was built in twelve weeks and the Voyager crew had to replicate it in two, resulting in the design being subtly simplified.
 * All in The Family - they decided to end the series, so they donated Archie's chair to the Smithsonian; when they decided to continue they had to recreate the chair. The chair originally cost like $2 from the Salvation Army, and the recreation cost thousands.
 * They did this to The Beverly Hillbillies's truck for the movie.
 * The original sets from Babylon 5 were kept in storage for many years in case of a sequel movie, revival, or in case Crusade got picked up by another network. Wouldn't ya know, shortly after they finally got rid of some of the sets due to storage costs, they get greenlighted for direct-to-DVD sequels?
 * When The Goodies moved from The BBC to ITV their new set was an almost identical copy of the original.
 * For Stargate SG-1, the sets from the Stargate movie of the missile silo used as Stargate Command and the Abydonian gate room were rebuilt. The producers did find the gate prop used in the film, but it had decayed and was only good for getting a mold to work off of.
 * The sitcom 8 Simple Rules once did a Actor Allusion involving John Ritter's character, where he had a nightmare that he was in an episode of Three's Company, complete with a rebuilt version of the apartment set from that show.
 * The Three's Company set was also rebuilt for a gag in Ritter's 1992 film Stay Tuned.
 * For the All Just a Dream ending to the last episode of Newhart, the bedroom set from The Bob Newhart Show was rebuilt.
 * The show's producers made a point of keeping the set hidden from the studio audience until the last possible moment while filming the episode, so as not to ruin the impact of The Reveal.

Video Games

 * For Fallout Tactics, everything had to be remodeled from scratch.