Another way of getting more water in her would be to feed her canned food. Cats are designed to get most of their water from food, not drinking and often don't feel the urge to drink even if they need it. I don't know what you feed your cat, but you might consider adding some canned food.
Dr. Seuss~DLH (brother's cat)~June 2007-
Misty~DSH (my cat & Mooby's mom)-?-
MooBoots(Mooby) ~ DMH(Mom's cat)~July 21, 2008-
Sunshine~ Golden retriever X white german sheperd (Dad's dog)~October 24, 2008-