I agree with Laur, impliment NILIF immediately. Since the couch is clearly a resource that he likes a lot, only let him lay there when you cue him to, and only cue him to after he's done some good behavior first. For example, he has to sit patiently and wait for the cue; or you can do a few training cues and then let him up as his reward.
I'd also play the "up and off" game - teach him that when you say "up" he needs to jump up on the couch, and when you say "off" he needs to jump down. Use treats and reward both the up and the off, and keep it upbeat and playful so that he has fun jumping up and off. If you practice this a lot,then when you actually need him to get off he will still think it's a game and happily get off (and then you'll reward him!).