Starbucks is my friend, too, and I'm sad to admit that I need it. I'm sorry to say, but there really is no way to fight our being tired. I mean, after all, most people are tired from just working a full-time job, let alone doing that and going to school as well (let's not forget those people who have families for whom they have to provide).
Working and attending law school at night is just something that you have to get used to, though I have to admit that even I am not used to it after two years of law school. Unfortunately, it will become even harder when you're a 3L, since that is when all of the On Campus Interviewing is going on, and it will be hard to fit that in, your classes, and your job; in fact, it may not be possible. Sorry that I couldn't be more encouraging, but that's just the way it is.