Here's a good website on dyspraxia: http://spectrumcenter.net/dyspraxia.html
The ballet classes can help your daughter in many ways, so by all means continue them, even if it looks like she's "never going to be a ballerina". First of all, most children who take ballet are never going to be ballerinas, but they love moving, it helps keep them active and develop balance, coordination, flexibility and muscle tone. (gotta tell my credentials here: I'm a Ph.D in dance, taught children for about 20 years, and now teach college-level dance and teach college students how to teach children's dance).
Make sure her teacher and the studio owner are aware of the dyspraxia, but I'd suggest giving them a quick run-down of what to expect--some teachers might be a bit wary of teaching a child with an unfamiliar condition; they might feel as if they're not equipped to handle it, but if you tell them what to expect, putting it in terms of what she CAN do rather than what she CAN'T, they'll accept her and help her. I had a college students with dyspraxia in my college-level ballroom dance class, and it was wonderful to see how everyone in the class was happy to be her partner, very patient and glad to help.
Having her in creative dance as well as ballet will help her to express herself non-verbally, as children with dyspraxia can have problems with verbal communication as well (But here I have to say that I'm definitely not an expert in dyspraxia or other learning or special needs areas, just a mom and a dance prof). And it will help her develop a good social network of friends.
Read up on it, and think in terms of what she CAN do, rather than what she can't. Best of luck!