Without knowing a little more about your girl, there's really no way of knowing/telling you what's going on. It could be husbandry... and then again, it could just be teenage angst. Around 900g, a lot of females slow down.... it hurts... but She'll get back on track!

You mentioned Rat Pups, and then you mentioned Mice..... If you're flip/flopping prey, then you can expect refusals.... stick with one prey item... If you're feeding Rats.... I wouldn't even let her SMELL a mouse..... Could get her stuck on mice for the rest of her life.... or for a long time anyway.