Deterring a cat from peeing in the same spot on the carpet using orange scent?

I got some oxy-orange to clean a urine spot on the carpet. It seemed to get rid of it but now the smell is back. I can't tell if it's the original urine or if they're re-soiling. I thought that citrus smells were good deterrents for cats. But the vet-tech thinks they will pee on top of smells they don't like to cover them up. Does anyone know if orange is a good deterrent to use on carpets? I'd like to shampoo certain areas to restrict them, but if they'll revolt my problem would be worse.