Vinegar! Jugs of it! Put it in a spray bottle and spray everything that smells. Get it nice and wet. Works great on carpet. I'm thinking about renting a steamer and using vinegar in it, if anyone knows wether this is possiblr, let me know. (sorry, nak)
It will really reek while the vinegar works its magic, but once that smell fades (a day or two), you won't even be able to smell the pee, provided you found all of the smelly spots. Even if you get right down there w/your nose.
We had a problem w/two of our kitties peeing on EVERYTHING earlier this year and vinegar is all I used. It is SO cheap and easy!!