make sure you spray the place(s) that he has peed on the couch with white vinegar - it works better if you don't dillute it. i hate the smell so what i would do is clean the spot with pet carpet cleaner, spray it with white vinegar, let it dry, then clean it again with the carpet cleaner to take away the vinegar smell.
letting the vinegar sit and dry will penetrate the spot and dissolve the urine smell so he won't smell the spot and pee there again.
keeping a litterbox in the den while he plays is an excellent idea, maybe even put a few of his poopy balls in it so he knows it's his.
good luck!!