I forgot to mention, it’s also very important to check the rest of your family members, even if they are not feeling itchy, just to make sure. The day after you’ve done the tedious and lengthy comb-out of the dead eggs, inspect her hair again and comb out more eggs, since you may have missed some in the first round. And, If your daughter ever babysits or works with small kids, she may have contacted it from them (the reason I’m so familiar with this process is that I worked as a kindergarten teaching assistant and I got lice from the kids). If she does babysit or work with small kids, encourage her to wear a hat or some kind of head covering. It might not look great, but it will help ensure she doesn’t get lice again.
also, make sure your daughter knows she shouldn’t feel bad about this—lice has nothign to do with clean or dirty hair, and it doesn’t reflect at all on her or her personal higiene. It’s just a yucky bit of bad luck.