Not true, Lilo from Lilo and Stitch started changing outfits about half way through the first season, and Nani wore something different almost every episode.
They're really hard to watch, and are just bad to the point of being cringe worthy, but that's just my opinion, and I've had to watch them multiple times to help a friend who's reviewing every individual episode of the series, so maybe you won't mind them, I don't know, but they are pretty bad, especially in contrast to the rest of the series
In the new version of littlest pet shop, hairstyles and clothing is changed. In a lot of newer things, there is continuity. I remembered a show with a character who always wore the same clothes, and when we saw his closet, it had multiple copies of the same clothes.
http://www.disneychannel-asia.com/DisneyChannel/supersites/kimpossible/games/shoppingavenger/index.html