My 14 year old cat is getting very slow and he just peed his cat bed last week which is part of what brought this to mind. We just put the whole bed into the washing machine with detergent, and wash it on hot, long, double wash - but we don't dry it at all in the dryer. We air dry it. So I guess we take the opposite approach
I'm sure in both cases the aim is to completely remove all traces of the pee smell so the cats don't begin to think of the bed as a normal litter place.
So far Hammie hasn't done it again, but I'm afraid his brain is fading ... he sort of hobbles around and limps slowly up the stairs. We'll do the best we can!