Yeah, I think so too.  Heaty. 

I bit my lips too when I am heaty. 

One time bite and bite and bite, 3 times within the same day. 

End up like been in a fight. 

OMG, bite 3 times on the same day. The ulcer must be big. I'm having ulcer now after bit my lips few days ago.

Not ulcer.  Just heaty. 

Chewing food then accidentally bite the lip.

As a result, that part of the lip was swollen.

Because it was swollen, it got bitten again. 

And again. 

I think it lies on your eating habit. No medicines are miracle if you don't change your eating habit.

You see.. the medicines or the remedies they suggest might be helping you to heal your lips in the process but if you are a fast eater and you don't change your eating habit, you will just end up the cycle of being bitten over and over again.

You should start eating your food slowly and think of eating as a relaxation, not just to fill your stomach. You should also stop choosing inappropriate times (like rush hours) to fill your stomach. You should really take time and eat your food. It's not like the world is going to end in 5 seconds or you are having an eating competition that you have to finish your food in a time given.

Even if you have bandage your lips all over, if you are not changing your eating habit, you will only end up getting bitten. I suggest you should take your time while eating. I think the best way to do so is to count around 30-45 times while you are eating(before you swallow your food). I know it's going to be really problematic and hassle but once you get used to it, i guess it will stop you from getting your tongue or lips bitten.

ya i know, b4 eating i always tell myself, eat carefully, identify the enemy, the food, not my lips, but still, "friendly fire" happens.

hmmm ok..
what about your jaw alignment? are they perfectly aligned to each other? Some people has slightly left or right(or front/back) alignment of their jaws (due to the abnormal growth position of teeth) and that teeth will always end up biting lips because of the mismatched alignment between the teeth

if you have this problem, i suggest you should consult doctor to correct the alignment for your jaw so that your upper teeth will match with your teeth below to chew your food easily(instead of biting lips or tongue)