Popularity Redo

You have a TV show, and it's not very popular. Maybe it's on a low-profile channel, maybe it's on at a bad time, maybe it's just not that accessible.

And suddenly all that changes.

You get a full season order on a better channel, or the powers that be have dusted the old thing off, but for whatever reason, suddenly your show has popularity potential.

Here's the thing, though--the old version has a lot of good material nobody saw. A scene you're proud of or a plotline you now have the resources to do better. So what do you do? Remake it for the new version, of course! Who's going to notice? No one. So you can see why this seems to be common practice.

Remaking the pilot or similar such things don't apply--the show had to have been an actual, watchable show during both versions for this to take effect.

Anime and Manga

 * The second season of Code Geass was completely reworked because, being very popular, it was moved from the midnight slot to a much more mainstream time, and a lot of the edgy stuff had to be removed. This is arguably the main reason why R2 had such hectic pacing.

Film

 * Tenacious D in The Pick of Destiny recycled many of the gags/themes of the HBO series.

Live Action TV

 * When Mystery Science Theater 3000 made the jump from local low-budget KTMA to the cable station Comedy Channel, they revisited movies from the KTMA era and reused some host sketches in their first season. Around season four they exhausted their stock of affordable KTMA-era films, and the repeat host sketches stopped by the second season.
 * The Adventures of Pete and Pete was a series of advertisements for Nickelodeon before becoming a series. Many of the one-minute shorts were expanded into half-hour episodes throughout the show's run.
 * When The Avengers market expanded to the US (it was previously an exclusively British show), many UK-only-era episodes were redone.

Newspaper Comics

 * There's a general tendency for a college newspaper comic that gets syndicated to simply redo old college material until the strip finds its feet. Bloom County borrowed a lot from The Academia Waltz, and Doonesbury also reused Yale-era gags for it's early years.
 * Charles Schulz borrowed a lot of the early gags in Peanuts from its predecessor strip Li'l Folks.

Radio

 * Around the time of its eighth season, The Goon Show remade a number of fourth-season episodes specifically for overseas sales, because the show was becoming successful in that market and the orginal recordings no longer existed.

Video Games

 * Metal Gear Solid is a Recycled Script based on Metal Gear 2: Solid Snake, a 2D game from eight years prior that was released in Japanese alone for a computer system that was not that popular to begin with and was already obsolete at the time of the game's release. The plot is cosmetically different, but the games share similar level design, gameplay obstacles and even a few identical puzzles.
 * Chrono Cross borrows elements from Radical Dreamers, originally released in Japanese for the Satellaview console. The Other Wiki states that director Masato Kato did Chrono Cross as an attempt to "redo Radical Dreamers properly."

Web Original

 * When Linkara transitioned Atop the Fourth Wall from text reviews to video reviews for That Guy With the Glasses, boosting his popularity tenfold, many such video reviews were simply him preforming the text reviews.
 * When Yu-Gi-Oh the Abridged Series began to hit its stride after the first few episodes, some of the older episodes were redone, making LK's Vocal Evolution very noticeable. He even did a live performance of the entire first episode from memory.
 * Team Four Star recently finished up their run with the first season of Dragon Ball Abridged. What did they do next? They abridged it again.  Cue Dragon Ball Z Kai Abridged.