You can of course keep her on mice, but please be aware as she gets bigger, she'll eat 5 or 6 mice in a sitting, maybe more.
At 900 grams, 10% of her weight is 90 grams, so she'd need 3-4 25 gram mice just to maintain her weight.
I'm not saying it can't be done, I know people here who have mice eaters, but you better be prepared for the work it involves.
Gale