We never get to see Citrusella, Nougetsia, Sticky and Torvald again after Sugar Rush reset. I mean, Citrusella and Sticky actually can be seen returning to the game. But after that, they disappear forever, as well the other recolors. Even their racing karts aren't in the game anymore. At first glance, I tought Disney just didn't want to animate them because they weren't important as the main racers, but I'm not sure about it. The recolors - according to all the Ralph Breaks the Internet trailers, promos and clips showcasing Sugar Rush - don't appear in the sequel. There are a few screenshots of the moment when the game is disabled. All the original racers are in Game Central Station but the recolored ones aren't. Also, there's a clip from the movie in wich the main racers are hosted in Felix's building. Again, no recolors there. My question is: what happened to them? Are they still alive? Did Disney forgot them?
It might just be a matter of keeping the scenes simpler. In Sugar Rush, there's plenty of room to show big groups of characters realistically populating such a large game. But Felix and Calhoun's half of the story in WIR 2 is mostly in Fix-It Felix Jr., so maybe it was just easier for the story crew to manage a lesser number of racers in such a small space. They probably didn't want to stretch everyone's screentime too thin, so they may have cut the recolors to give the rest of the more prominent racers a chance to have more lines.
Since they only really had notable screentime in the first movie's scene where all the racers are putting their coins in the pot to enter the race, it could be that the recolors were at the bottom of the hierarchy as far as necessary characters go (i.e. they obviously can't cut main characters like Ralph, Vanellope, Felix, and Calhoun, or notable minor characters who would have a reason to return, like Surge Protector or Taffyta). If someone needed to be cut for simplicity, it would be the most minor characters who didn't already have dialogue or established personalities.
Those are my guesses, at least. I doubt Rich Moore or the other crew members forgot about the recolors, because they mentioned that they'd re-watched and studied the movie before making the sequel.