We use tea tree oil and apple cinder vinegar. I normally takes about a week for them to disapear. If it is bothering you alot I would recommend that you also go see you family doctor.
There are over the counter products for regular skin warts, but these should not be used on lips. You should see a family practice or dermatologist doctor for a lip wart removal.
Are you certain they are warts? Or could they possibly be cold sores from the herpes virus? No matter the cause it would be best to visit your doctor or dermatolgist for removal.