I've been in the same shoe. The fact that she doesn't smoke around you means that she's aware that you're put off by it, and she may even be aware that you're willing to make the relationship work with her, even though you normally wouldn't date smokers. There are more subtle things that you can do to encourage her to quit, like avoid kissing her or getting close to her after she's had a cigarette. I usually cough or complain when I pass by a cloud of smokers as we're walking down the street together (when he's not also smoking). He eventually quit for whatever reason, but I can't help but feel that I was a motivating component to that decision.
