A short course (generally somewhere between one and three weeks) of medication should clear up an infection such as this. Your cat should have started to improve within a few days of starting the antibiotics but it may take up to three weeks to clear up completely. If the infection (and accompanying incontinence) has not cleared up before the end of the course of medication then you need to take your cat back to the vet. There is some evidence that cranberry juice can help treat/prevent urinary infections so it might be worth giving your cat a small amount every day (you can get capsules if she doesn’t like the taste).