I started back at school recently and I've had the same dilemma! The good thing about vegan food is it can get to room temp and still be safe to eat most of the time. I usually just eat out of a tupperware container and I find that leftovers are the most filling, and keep me full for a while. Here is what I've been taking so far:
Leftover veggie pasta casserole
Cooked plain quinoa with a chopped up leftover homemade black bean burger with salad dressing
Tofurky and veganaise sandwich (not sure if this is safe for an extended period of time but I eat it within a few hours and I'm still alive!)
Tofu fried rice leftovers
PB&J with soy yogurt
I keep soy yogurts in the freezer and by lunch time they are defrosted and still cold! They also keep the rest of your lunch cool too if you need it.
I also pack some kind of snacks like lemon or ginger snaps, or a homemade muffin. This week it was Almond Quinoa muffins YUM!