I wish I had some good advice for you. We are in the same situation and have decided only ripping out the carpet completely is going to get rid of it. We have a carpet shampoo machine that we used several times, used a gallon of nautres miricle on it and it did nothing and even had a carpet cleaning company come out and clean it. You can still smell the pee. If it gets into the pad, there is nothing you can do but rip out the carpet.