Egyptology is one of those special fields that really doesn't coincide with high school's code of generality, so it is really hard to say; however, if I had a second chance, I know I would have taken all of the foreign language classes I could. A good grasp of languages other than your native tongue will help you gather resources from texts that might not be translated into English, and will help you when learning that pesky language of Coptic (a mix of Latin and Hieroglyph; looks almost Arabic - but .. Demonic is more Arabic, I suppose). Ancient history classes would be quite helpful, as well. Remember, people love to travel; explore; see the sights. Hatsepshut traveled to the land of Punt to trade for exotic goods, but no one is quite sure where this land might have lain. With a clear view of not only Egypt, but the surrounding world, your daughter might one day crack this mystery. A.P. English isn't a must, but in order for her to articulate her findings past a drudgery of, "I found this totally awesome site, man. It has mummies and stuff, I think it might be the funerary tomb for one of Tutankhaten's wives." It's really a matter of a respectable image, that one. Also, classes dealing with Anthropology are key; especially if your daughter wants to deal with mummies.
There are different kinds of Egyptologists. There are those who seek tomb and treasure, hoping to find missing pieces of the past, others who study the local life, rather than the royalty, and then there are those like myself, who strive to put a scholarly tongue unto the field, whilst understanding the actual words that were written so long ago.
So, for now.. try to have her in a generalized field. It won't be until later that she'll know for sure what she wants to study in Egyptology; the people, the land, or the writing?
I hope this helps, and I wish both you and your daughter the best of luck!