The second thing that occurs to me is that there may be something going on that is so threatening to your daughter that she is unable to discuss this with you, or anyone else. This may be something social, something sexual or some other kind of moral dilemma. Keeping the door open to communicating with her is essential. Letting her know that you are always ready to talk with her and that you will not punish her for what she tells you is very important. Suggesting that she might talk with a psychologist or a therapist..who is not connected to the school, and where she will have complete confidentiality might also help.
You didn't mention anything about your family and I am wondering if there are any major changes that have occurred in your family (marriage, divorce, death, illness, moving house) in the past several months. These changes can often be the source of stress in our children's lives, even if on the surface they seem to have adjusted to the change.
In order to help your daughter make it back to school, it is important to set up very clear rules with her. Addressing the issues of when she is allowed to miss school, and what she needs to do when and if she misses school is important. Running a fever is often a good benchmark to use in deciding whether to allow your child to stay home. Stomach aches and headaches are usually not good indicators for staying home. When your daughter does stay home, guidelines as to how much TV? - watching and computer? - playing is allowed are also helpful. Reminding her about homework and schoolwork she needs to make up and making yourself available to help her with this are also advisable.
If all this fails and you can't find a "correctable" problem, I suggest that you contact the school psychologist in your school district. These professionals usually have experience with school refusal, as this problem is called in the professional jargon. They may be able to help you and help your daughter get back on the road to school.
Good luck and let me know how things go.
Naomi L. Baum, PhD