Four times a week is pretty good. It won't help burn stomach fat, though, there's no way to pick where you burn fat from.
I get back on track all the time. I usually go into maintenance for a few months and when I feel like my batteries are full, I start dieting again. First, I just count calories, not necessarily trying to eat at under maintenance. I visit the forum and other sites, I up my activity levels. Usually, after a few days I convince myself to get on track.