The worst thing you can possibly do is bring too much attention to the "problem". She'll feel more pressured and be even less likely to get there. I'd be willing to bet that she's very self conscious, and this is a big factor. She doesn't seem to like oral much, she may think it's dirty, smelly, bad tasting... Little does she know it's not and some guys love every bit of it. Try oral shortly after showering. Try making love in complete darkness, maybe she's not happy with the way she looks? Tell her how great her new hairstyle looks, how well those pants show her curves... Build up her trust in you over time and she'll be more likely to open up. Oh, and get her drunk
She'll be less inhibited and more likely to really let go and enjoy herself... Just make sure she doesn't get too wasted, that'll ruin the whole night!