caelric has it right that you need to practice nutrition. Get a bento box for you bike. I love honey stinger products (waffles and chews on the bike and there gels for the run). The way you train should change slightly beyond just adding distance. I would make sure that you include brick workouts (run off the bike) if you don't already. Remember that they way you race is much different. For a sprint you can pretty much go all out start to finish, but for a half or full you need to never push it too hard. A HR monitor is very inexpensive and helps to isolate which zone you are working in. Again, if you don't already have one you should consider getting one and using it.