What is the Best Option for the Indented Scar Under my Lip? (photo)

Your treatment options... already listed above are to consider further resurfacing with a laser or dermabrasion, vs filler, vs scar excision and reclosure. If you have not much improvement with the laser, consider a more aggressive laser resurfacing option and/or the surgical option. Good luck. 

An option for you may be to undergo a scar revision or laser resurfacing.  I would recommend that you consult with a board certified facial plastic surgeon to discuss you options.  

A great option for the indented scar on your lip is to undergo surgical scar revision with layered closure of the area.  This will recreate the normal contours of the skin. 

Depressed Scars Respond Well to A Combination of Subcision and Medical Microneedling

Depressed scars, regardless of the prior cause (surgical, traumatic, acne, infectious) generally have two main aspects that must be addressed by treatment in order to achieve a gratifying aesthetic result.

The first goal is to lift the depression itself as much as possible to achieve smoother skin. The appearance of any depressed area of skin (whether due to a scar, wrinkle or fold) is accentuated by what is known as the "craters on the moon" effect. The shadows cast from side lighting darken the base of the scar, and, it's a rule that makeup experts know well and put to good use that anything that lightens an area increases the illusion of being outwardly projecting. A white makeup pencil can lighten the base of a scar and make it seem less depressed. But, this is of course temporary.

Subcision, however, can be used if we are looking for a more permanent solution. Subcision is a process whereby a small cutting needle is inserted directly under the scar  (following the administration of local anesthetic) in order to break up the thick fibrous scar bands that  pull the surface downward. At the same time, we create a space for new, healthier collagen to be laid down to fill, bolster, and elevate the base of the scar and smooth it with the surrounding normal skin.

Scar tissue typically possesses and an abnormal ivory-like color and abnormal surface texture. Medical microneedling, which creates columns of perforations through the skin down to the dermis, can be used to address these issues, if desired, This treatment involves the use of an array of sterile needles that are rolled over the scar (following local or topical anesthetic application). On a microscopic level, and in a fractionnated pattern, the needles  break up the abnormal surface characteristics and coloration and permit the development of a more even coloration and texture following healing. To hasten the process, not uncommonly, subcision is combined with medical microneedling at the same treatment session. The advantage of these approaches over the use of a filler is that the results of both subcision and microneedling are permanent.

I would say that you have two options for improving the depressed scar below your lip.  You could have a filler injected into it to try and raise it, or you can have a scar revision procedure in an attempt to get a thin, linear scar.  Depending on the filler used, the results most likely would be temporary, while the surgical option should be permanent.    

The picture posted seems to show misallignement of the white roll line of the lip.

You will do better with scar revision