Is she in good condition? IE - does she have good weight on her?

If so, tough love is what I used to get all of mine converted to rats (I used to just a mouser). Each week - offer an appropriately sized rat. She doesn't take it, she doesn't eat. After about four or five weeks - they're hungry enough to eat. If you give in and feed a mouse - start over with the tough love.

Another trick, get some mouse bedding (ask the pet store for some in a bag) and put a handful in the enclosure. Watch for her to start hunting and drop in the rat.