Go back to day one. And take heart, he's older and will learn quickly once you stop bad training. Yeah, the problem is training not the dog.
Housebreaking fails usually because the people doing it don't put the effort needed. A dog that is not fully (not 80 percent, not 90 percent not even 99.9 percent) housebroken requires that you are watching or confining the dog every single second. The good news is once you do it right, you are pretty much done.
http://www.ehow.co.uk/about_6120814_housebreaking-difficult_.html
1. Keep the dog crated, watching it, or tied to you at all times. When it wakes up, plays and eats, take him out just as you would a young puppy.
2. Use a happy tone to praise when he potties outside. Some don't like using treats, but I think with this age dog it may provide that extra motivation for outside only.
3. Did I mention watch all the time? That's the boring but critical part. Look for signs he has to go. If you know early morning, either move feeding to much later so he doesn't have to go so early or set clock to take out early, or take out much later than you usually do.
Every accident increases the learning to potty in the house. It may be a rough month getting past this, but if you are diligent, you can stop it.