You know, elasti, something I have found that really kills my craving for sweets, especially donuts, is a toasted whole wheat english muffin with flaxseed butter and apple butter. It's delicious and very filling.
The way I see it though, there's no need to "restart" or "punish" every time you have a piece of birthday cake. I think before you eat something, it's important to ask:
1) Do I really want this? - So often we're just eating to eat, because it's noon and the guys at work are making a McDonald's run. I've learned through time although it's incredibly sweet they think of me to offer, that it's worth 15 minutes out of my day to go to Quizno's or Subway and get a veggie sub without cheese.
2) Is this "the best?" - I never eat anything that isn't delicious. Doesn't mean I'm a food snob. Sometimes with office supplies we get free cookies (Mrs. Fields). It was a great pleasure to me to eat six of those little mini cookies, loaded with preservatives and other crap. I could have beaten myself up, but instead I enjoyed the cookies, skipped lunch, and had a nutritious dinner. It's easiest for me if I correct "unhealthy" behaviors right then, in the midst of the behavior. I could have gone on eating cookies, but I was full. I could have had lunch, but frankly, I'd had enough to eat and could just bank on a healthy dinner of whole wheat bread and eggplant parmesan. I don't regret eating cookies for lunch or view it as a setback, but just a necessary switchup in routine from a healthy lunch!