6 months post op, what can be done to treat persistent bruising on cheek after upper facelift? (photo)

The treatments you have had, are all good. The laser treatment will also be helpful. I would add mild heat and massage twice daily and a bleaching cream like hydroquinone. It takes up to a year to heal, so more changes will occur over this time.

It would be helpful to see pictures from before and along the way if you have them. Regular bruising is simply the visualization of pigments that form as hemoglobin is converted to the end product of the breakdown of red blood cells which is bile. This transformation typically does not last that long. The time frame depends on how much blood is left in the tissues. If discoloration persists then it may not be the intermediaries in the hemoglobin breakdown process but rather a different mechanism like hemosiderin deposits which is the staining of tissues from the iron in hemoglobin.
Usually the best course of action is to give it time. Attempted intervention can have undesirable side effects. Anti inflammatory steroid injections are not typically indicated to treat postoperative discoloration.
Consider consulting with a board certified dermatologist in your community. Bring pictures if you or your provider has them.
Mats Hagström MD