We had a dog who was extremely prone to urinary tract infections, and solved this problem by giving her cranberry extract pills. I'm not at all sure how one would go about getting a cat to swallow something like that (they were large, and not splittable, and we're having enough trouble getting halved Flagyl tablets into one of our cats even with a piller), but if it can be done it might speed your cat toward not having such an infection any longer, and might be good to keep on hand should she get another one when you haven't got immediate access to a vet for whatever reason.