I have quite a bit of experience lucid dreaming and could give you some pointers if you message me and remind me, I don't have time to go into it now. Bottom line, in my opinion, is that dreams are about our expectations more than our hang-ups, so successful lucid dreaming is simply a matter of suspending your disbelief in the "impossible" and expecting it to be possible. "I know I can fly" vs. "I want to fly even though I can't."
I never tried to heal myself in a dream, but have changed the structure of my face while looking in a mirror, so that would be what I would do with the lips if I remembered it in the dream. I know my lips will be perfect from now on -- perfect starting now.