I agree with Kathy F.'s response. Find out why & what is bothering her.
For my daughter, I know that if she tells me something like this, it IS for a REAL reason. I know she isn't just pretending. One time for example, my daughter for a period of a couple months, refused to go to PE class or school. And she was crying/clingy/fearful/upset/tantrums and the whole 9 yards. Instead of dismissing her as a "hissy fit" queen... I told her I would find out why & we talked about it together... I talked with her teacher, I talked with the school counselor, I talked with her PE teacher etc. It took some poking around on my part and keeping a dialog going with my girl...then one day, she finally told me that she HATED school/PE class because "the Coach has a loud voice... and he's scary.... and it's so hot and he doesn't let us drink water... and he doesn't let us use the bathroom... and we have to do everything PERFECT- trying our best isn't enough- it has to be perfect...." SO, this is why my girl was basically getting major stressed out just from this one PE Teacher. AND it took at least a couple of months for me to learn this and figure it out. Apparently, as I later learned, it wasn't just MY girl having this problem... it was other kids too. And later, after my trouble-shooting it and making mention of this to the school... and other feedback from Parents... the teacher was disciplined. So, you see, kids do have real reasons too.....
You've tried everything else... so why don't you try the route you haven't tried...and actually try and "see" what may be the issue.
Just hang out at the school... see what goes on there... sometimes parents don't really know what happens in class, how the teacher is, what the kids do, what the classmates are like, or what the "problems" are, because they don't even "see" the class or observe the classroom.
Next, once you find out the why's for her not enjoying school, and it can be "solved" and happily....have you considered sending her to school maybe 3-days a week and then gradually, everyday?
This might be a good thing. Because, if only going 2 times per week...a child is basically having to "catch up" and re-adjust to school each time... simply because their exposure to the school/class routine is so limited. Then they don't really get a chance to make friends or get in the full swing of things, so to speak. So, perhaps this also affects the child's ability to "get used to" the newness of the "new" teachers and kids and classroom. And it can stall things.
A great book is called : "Your 4 Year Old" (you can get it from Amazon.com).
I'm sure it will be fine...but this age, it's not easy. Girls too, are emotional little creatures and so tender. Sure they cry... but they also need to learn that if they cry, and IF it is for a good reason, their Mom will listen to them and do something about it too.
Good luck,
Susan