Did you change anything in the way you kept her? Have you started purchasing f/t rodents from a different place?

I've seen some switch from f/t and not go back, it's not highly common but it's been known to happen. I know that some can be picky about the color of the rat. If she was eating all white rodents, maybe make sure she's eating an all white one.

At the end of the day though it's just how ball pythons are.