If he isn't ready to do the work, he isn't ready. There has never been a single drug addict that got there on their very first attempt. Unfortunately, it takes a lot of failure to succeed. We try out so many different things so many times before we can finally accept that we are powerless. And that is exactly what we truly are. We are out of control in every aspect. Of our lives, of our relationships, of our drug use, etc. We no longer control a damn thing. We are controlled by our need for the drugs. When you talk to an active addict, you aren't talking to the addict. None of us were born junkies. The lifestyle changes everything about us, and not for the better. That is why you have a hard time accepting the things your children say and do now as opposed to who they were before drugs. They are two different people. We aren't lost forever, though. We are somewhere, buried deep. Once your son is ready to admit and accept his powerlessness, he will be ready to make true strides forward. Recovery is a "two steps forward, one step back" kind of thing, but that IS progress. Relapse can be progress, so long as we learn something from it.
Once he is ready, doing the work wont be something he avoids, but embraces. If he isn't there yet, so be it. You are always right there, ready to do whatever you can to help him improve. He may be choosing to play Russian roulette, but you don't have to help load the gun.
