Depression in lip after mucocele removal. What can fix it?

My suggestion is that you wait for at least 6 months, longer is even better, until your lips are stable and soft to see what the final outcome is. If still depressed then a fat transfer by lipoinjection may be your best option. See a board certified plastic surgeon for a recommendation.

While injectable fillers can provide a temporary fix, small fat grafts placed into the lip indentations will provide a permanent solution.

Depending on the size and position of your lip depressions, you likely have a few treatment options.  Surgical rearrangement of tissue (a local flap, in other words) may be appropriate.  A variety of filler may also be used to fill in the depressed spots; most hyaluronic acid (HA) fillers, such as Juvederm, Belotero, or Restylane, may be used (off-label) in the lip.  A permanent filler, such as medical-grade silicone, may also be used.  Some practitioners will harvest fat or SMAS (a collagen-fat tissue in the face) and use these as grafts in the lip.  You would be best served by an in-person consultation and exam with an experienced facial or general plastic surgeon who has a keen understanding of facial anatomy and lip treatment.  Such a consult is a key first step in understanding your options, with the benefits and drawbacks of each.  Good luck!