B.G.
Do you think she is holding it in all day and then finally goes when her body relaxes? If that's the case, you could try adding fiber to her diet. Maybe apple juice in the morning is not enough.
When my neices were "holding it in" my SIL drastically increased the fiber in their diet. I think she even used Miralax for a few days. They also stayed home for a few days. Because their stools were very soft, they really couldn't hold it in as well and had to go. Then it was just a matter of helping them to see that going in the toilet wasn't as scarry as they thought.
Just to let you know, this is a very common hurdle. Many kids take awhile to poop in the toilet. Both my kids requested a diaper for the first few days of potty training. My oldest (thankfully) gave in and tried the toilet. With my youngest I was not so lucky. He took a couple of weeks. Fortunately we had some of his brother's old underwear, so when he did poop I just threw them away. Now that he's got the hang of it he can wear the new ones he picked out. Hey, we were going to throw those away anyway! A friend of mine decided she was done washing out undies and bought a bunch from the dollar store. She used them just like disposable diapers and threw them out each time :-) Whatever gets you through it.
Good luck!