J. - you are preaching to the choir on this one. I have the princess of all princesses and we are just finishing our kindergarten year at a private school where she wears blue plaid jumpers, skorts, shorts or slacks. She only wants the jumpers - therefore we wear little shorts under them and the skorts. I have not had a battle yet with getting her dressed in the morning. Even the hair accessories are uniformed and so are the shoes and socks / tights. She has really enjoyed seeing what her other friends are going to wear that day too. I thought that I would have to have "special" weekend clothes for her to make her feel like the princess, but all it took was letting her pick out her own panties that she could wear and no one would see.
She also is not allowed nail polish she she really looks forward to the weekends when she can wear it.
You have to get your daughter to understand that she is now a big girl and big girls who go to school, not day school, have to dress like that.
Our school also has uniform break days where the children are allowed to dress in regular clothes but still stay in compliance with requirements - belts on pants and shirts tucked in. On these days my little one loves to wear her pink skirts and dresses or even her "pink" blue jeans.
The private school my daughter is going to they have the kindergarten students come in for a shorter first day in small groups - we had 4 in our group. Those are the students that she is still closest to in her class. She has a total of 15 in her class. This way by having small groups they can get to know someone special - we had 2 girls / 2 boys. This was the first day that my daughter had ever been away from her daycare friends - they all went to different schools.
Good luck.