I have a daughter with a long hair and a sensative head. I feel your "pain!" However, we decided not to cut it. Little girls are only little girls once in their life. Short hair means no ponytails, cute bows, or pulling it back. And in the long run when you can't pull it back it is more of a headache. You still have to comb it, but it is just more tangled from being down all day! LOL So here is what I do, and it works great.
I would do the following:
Give it a good trim, just taking off the split ends. The following hair products from Sally's are great, and not expensive. They often run "two for one" sales on them. And the ladies there are great to help you find just the right type product for your hair. The brand I use is ION. We use swimmer's shampoo in the summer, and vitalizing shampoo the rest of the year. (Use what is appropriate for you, of course!) Next, do a good conditioner every other day, light on the top of head to prevent oily hair, heavy on the bottom, to eleminate exessive tangling. On the days you don't use a conditioner, use a "cream rinse detangler." After you do all this, brush it with a "long hair brush." This is also available at Sally's it has a large square head. (You can get it at Walmart, but I recommend Sally's. My daughter complains about the one we had got from Walmart, and it fell apart sooner. They are really about the same price.) When brushing it, spray on the ION leave in conditioner. Do this again in the am when you are fixing your hair for the day. Once a month, I would do a heavy conditioning treatment. It comes in a packet, usually found at the register. Put it in your daughter's hair, put on a disposable plastic cap, and let her play in the tub for about five minutes. You'll be amazed at how soft and managable her hair will become! We call this "our beauty treatment." She thinks she is really doing something big!!!
I know this sounds like a lot of trouble, but it really isn't. It takes five minutes tops to do all of this everyday. And I find when I'm spending this time with my daughter doing her hair, I can talk to her about stuff. "Girl stuff." She has come to like it and so have I. What a better way to bond, huh? And maybe she can keep that little girl hair longer. Let me know if you have any questions about any of the product I mentioned! I would be happy to e-mail you exact names!
Take care! ~Lee, ____@____.com