If you bury/spread a thin layer of lava rock in the problem areas it fixes the problem immediatly- at least it did for us. Let me know if it works for you!
Lava rock (as Chelby mentioned), pea gravel, river rock are all good. If she's tough and digging through rocks, add a layer of chicken wire on top of the pebbles. You can bury all these a couple inches deep and replant your grass on top.