If it is hormonal, keeping other triggers at lower levels may help. Many people have migraines related to foods, specifically: pork, especially ham and bacon, strong cheeses, chocolate, caffeine, citrus and others. Some odors can make some of the sensory things worse. My vision, hearing and sense of smell all seem more acute during a migraine; and certain scents can make me feel very ill.
If they are related to hormone levels, chart the headaches in relation to your daughter's period. Some people have headaches when they ovulate, some as a PMS symtom and some with their period. If this is the cause, regulating the hormones will help; this usually means birth control pills. It also maybe that when the hormone storms of adolescense and puberty (sorry about the spelling) are over, the migraines will go away on their own.
I'm so sorry she is going through this. I suspect that my ten-year-old boy gets migraines, but if he just says he has a headache and doesn't want to play, its hard to tell.