Lip glosses are messiahs:
Choose a strong flavor of lip gloss and try to keep it on every time. Though you may not like it but most preferably choose a flavor you are not very fond of. The next time you lower your teeth on the flesh, goes the distaste and you are done with the whole idea. Keeping lip gloss on all the time might seem as a bit too much effort but keep a gloss in your bad, near your bed and places you visit frequently. This way you will not forget to use it. Once your mind gets used to the idea of not biting your lips, you can give up on the gloss safely.
Much that you find the idea revolting, apply lotion to your lips. Your teeth will not like it there anymore. Not only will you get rid of bruised and charred lips but will also have softer fuller ones, enhancing your face appeal.
Lemon saves the town:
Apply lemon juice on your lips. It will heal the soreness the biting created and will also stop you from biting more with its strong taste. The tip does not apply to people who like to taste strong lemon once in a while.
Cut the source:
Lip biting mostly happens when one is in stress. So it is better to remove the cause first before moving to symptoms. Relax, take a warm bath and get over the stress. Be with people you love and who make life feel good.
The need is to chew apparently. But it does not necessarily have to be your own lips. Get mint, gum and candies of your favorite flavors. Stock them in your bag and whenever you feel like chewing, help yourself. A busy mouth does not turn to the lips when it has work to be done.