She probably sees that her crying affects you. She would rather be with you than at pre-school. She thinks she's missing something. Kids have this amazing ability to adjust to whatever works on us. It's not malicious - it's inborn. If it's worked before she'll try it again - it might work again.
On a day that she doesn't go to preschool or after she's come home have a conversation with her. Ask her why she cries. Ask her to be specific "what makes you unhappy about pre-school?" Is someone mean to you? if so, who? what does she/he do that's mean? (Don't be surpirsed if she makes stuff up at th is point so you'll change your mind about preschool.) Suggest that you and she talk to the teacher together about a child that's making her uncomfortable (prepare the teacher ahead of time). Expect that she may demure once you offer to involve the teacher. Ask her if it's becuase she misses you, or soemthing else. Explain to her that when she's at pre-school you're doing boring stuff - you're working, or cleaning, or other things she doesn't like. Ask if she wants a photo of you to have in her bag? or offer a transitional object like a special stuffed animal (with your cologne?)
Don't dwell on her sad emotions - ask about it then move to the next thing: Setting expectations.
Once she has seen that you're listening to her and care about her opinion then set your expectations for her - in a positive way. Tell her you know that since she's becoming a big girl now you know she's going to be able to go to preschool and have a good time, and that you'll always come to get her & would never leave her there. Tell her that when she goes to preschool the next time (tomorrow, the day after?) that you know she's going to be a big girl and go right in without crying. Encourage & praise her. Tell her you know that she's going to find some fun things about preschool, and she's going to think about those things - not the things that make her sad.
Then remind her of those expectations before she goes to bed, then again in the morning while you're having breakfast. Then one more time as you drive to preschool. It's all about the positive - stay upbeat - remind her how proud you are of her as she's becoming a bigger girl and doing things that babies can't do (give examples). It's always about the positive, not the negative. As you walk in, hand in hand, tell her how excited you are to know that she's going to be so grown up as she goes to school. Smile, hug and leave. FAST.
When you pick her up late exaggerate your delight in her ability to act like a big girl. give her an enormous hug, kisses on her check, tousle her hair. PRaise her in the presence of her teacher, praise her as you walk out to the car. Tell dad at dinner time how well she handled pre-school that morning. And again at bed time.
We all respond to positive - we want to know we're doing well. As the days go by contineu to set expectations and praise afterwards - but taper in off in less than a week.
An 80 year old Sunday school teacher taught me this when my daughter was not quite 3. I've suggested it to other moms (when I was teaching Sunday school) it works with bigger kids too, 8 - 12. It's like magic.
You'll both get past this - but man it's tough. These kids of ours know exactly what works on us!
