I am half Mexican, half Caucasian and my whole life had dark hair on my upper lips and between my eyebrows. My mom, who is white, didn't let me do anything about it for awhile, but when I was about 11 or 12, I started removing the hair on my lip and in between my eyebrows. It was just so overpowering for my face and I noticed it from such a young age. I now get my eyebrows waxed every couple of weeks. I would reassure her she is beautiful, but also when you feel she is ready, let her try some of the products if it really bothers her. I know it helped me feel so much more confident.
Another thing that really helped is visiting places where women who were considered beautiful looked like me. I grew up in Missouri and rarely saw anyone with darker hair and skin besides my African American friends and people in my family.
All my best friends were tiny blond haired blue eyed girls and that seemed to be the only "beautiful" until I started going to places where women who were looked at as beautiful were not the cookie cutter Midwest idea of beauty. I then began to realize beauty could have many forms and that also made me more confident. That's something that you can do with her now and she doesn't need to be a certain age to do. It doesn't have to be overt, but just spending time in a place where people looked more like me was very helpful.
Best of luck with your daughter!