madison - have you tried the 4% hydroquinine or are you just using something over the counter? I get the hormonal melasma over the lip, but 3 months of Obagi Clear 4% zapped that. I also know that if I step into the sun with no protection, it would be back in a flash, so I carrie a small chapstick type tube of spf in my purse if I'm to be out all day at a Summer/sunny event.
I also like the Pigment of Your Imagination by Philosophy that Dr. Baumann recommends. It's heavier/greasier, but I noticed some lightening of sun spots when I started using it.