Repeated twitching of any muscle is often related to a problem of either the muscle itself or the nerve(s) leading to that muscle.
Any muscle, that can be voluntarily moved, is capable of sustaining fasciculations every now and then, or repeatedly throughout the day
The more you worry and obsess about your lip, and the more you examine it in a mirror, the more likely it will twitch away. Dehydration
and a shortage of magnesium
and potassium can cause fasciculations.
Take a CT brain to rule out neurological cause. If no problem is there - forget it, it will become automatically alright in course of time and a balanced healty diet containing antioxidants
and potassium. You an take antioxidant tabs also.
It will run its course and settle down.