You could try a softer litter, like Yesterday's News or SWheat Scoop. Both clump, but without the harmful sodium benzoate(sp?). Kittens under 4 months should NEVER use regular clay grocery store clumping litter. It can, and has, killed them.
Also, maybe you could put a paper towel with her urine on it under the litter. That might attract her.
Also, maybe you could put a paper towel with her urine on it under the litter. That might attract her.