She only had one noticeable role ("New Kid on the Block"). After that, she mysteriously disappeared ("Mr. Plow" and onward). It's an odd removal, but Bart just forgot about her within a week after November 12, 1992.
She only was mentioned by her mom in "Marge on the Lam" (Lionel Hutz was the babysitter, for who knows why) and I think she had two cameos in "The Simpsons Movie". Flashback in "Simpsons Clip Show".
Is there perhaps any information regarding this? It is odd how she and her mom are not recurring characters in the show.