I had a long period of sobriety and drank and it took 4 and a half years to get sober again. I had stopped going to AA quite a while before I started to drink again, and I was resistant to going back so I had to try everything else first. There was no real reason I didn't want to go back other than stubbornness and trying to do it "my way".
It wasn't until I really gave up and went back to meetings regularly that I could stay sober. That was what I needed to help reinforce living sober again. This site, of course, has also played a big part in helping me to stay on track this time. I've not had to pick up a drink for over 2 years now.