I really like what so many posters have already advised, especially Peg.
As a preschool teacher, I do advise parents to keep with their scheduled days unless their child is truly having an *off* day or is ill. My first reason is consistency for the child as well as our community. The second reason is simply this: later in life, school attendance is not an option. (Unless you choose to take on homeschooling.) Imagine how hard the future would be if children felt they had a say in the matter on a daily basis.
As a mom, I have a little boy your daughter's age who goes to my girlfriend's preschool. Just this morning he told me he wanted to stay home at "mama's school". While the heartstrings were tugged, I gently told him "I know, you have a lot of fun at home. Today is a school day, and when our four days are done, you get to stay home with mama." While I would have loved to have kept him with me (he does well with my other students), he needs a mama who will stand firm and be consistent with him. He needs the predictability and he needs me to be in charge, even when he isn't really wanting to do what I ask, because if I'm not in charge, who is?
I don't know your daughter well enough to suggest anything beyond what you and your daughter's teacher will try to work out for her. It will help the teacher immensely if you decide to be a team to help her draw your daughter into the group play. I'll also add that, at this age, some children do a lot of observing and may continue with parallel play for a while, so please do not think of your daughter as anti-social. Perhaps introverted? (There's a great book called The Introvert Advantage which I highly recommend. Introversion used to be considered an anti-social behavior; it has since been better understood and we now know why that categorization is incorrect.) An anti-social child will be acting out toward other children--either openly or on the sly-- and exhibit other concerning traits, and you aren't mentioning these. So keep on as a team with the teacher--- one thing I would find helpful from a parent would be to discuss what sort of activities your daughter enjoys at home, so I could incorporate a bit of that into what I'm offering at school, and then to figure out how I could offer it in a very managed group play setting.
Beyond that, this is going to be her challenge to master--finding a way to feel okay at school. This isn't easy for every child. Last session, I had a child who had a very difficult time being at school. When the child returned this session, we changed a few small pieces of the routine and it was literally a night-and-day difference. Talk to the teacher, too, and see if she has any suggestions for the drop-off. I have found that tweaking my routine has helped *monumentally*. The parents no longer come into the school space; instead, they say their goodbyes outside and I greet the children on the porch. The kids carry their own coats, backpacks, lunchboxes, etc, then come in, put these items in their place, use the toilet and wash hands just fine all with direction from me, instead of having Mama do it with/for them. It has made a HUGE difference in the children seeing themselves as capable and competent players at school!
Best wishes,
H. Wheeler
owner/teacher
Plumtree Nursery School