I'd just wait it out. Many people consider a 60 gram rat plenty for any ball, so she may have just had her fill of rats for a while. She also could just be hitting the 1000 gram wall. Seems a lot of girls will turn picky once they hit the 1000 gram mark. I've got a couple of girls over here that were garbage disposals, but once they hit that wall they've turned into pretty picky eaters.