Since your top lip is thin I would not try to "correct" the lip by placing too much filler. A small amount of Botox injected would correct the "gummy" smile and a syringe of Belotero would help plump up your upper lip. I would not expect a full correction upper lip but rather an overall improvement in the lip fullness.
You are correct in the way you are thinking about this. A lip lift would probably not be a good option for you in that you would get even more gum show. A small amount of Botox in the upper lip done by someone familiar with this technique (not done very often) might be helpful. It is true that the thinner the lip, the harder it is to get the filler to give you the result you want. With that said, it certainly looks from your photos that another try with Restylane or Juvederm might be helpful. If placed far enough inside the upper lip, it should roll the lip out and lengthen the lip slightly from top to bottom, correcting both issues. I wouldn't give up on filler yet. I would find a very experienced injector, talk about your specific concerns and recent outcome, and you may be happier with the results. Good luck.
Try BOTOX to upper lip near nose to release the constricting muscle for a gummy smile correction. Additional HA filler to upper red lip like Belotero Balance 1 syringe..