I have to agree with the consensus so far... Basically, like what's been said so far (or what I've at least comprehended from what I read), I'd give her one last shot.
I mean, it kinda sucks, because now it gives her a feeling like you can't entirely trust her anymore and she has a shorter leash. So, I'd be sure to clarify that you can still trust her (if you still do, which I assume that you do), and that it isn't even something that should even be brought to attention. Perhaps I should clarify... There's no need she would have to think about the idea of only having one chance left, unless she was tempted to do it again. It's really just a non-issue. Kind of like the game. (sorry, you lost.) You know about it, but once you think about it again, you lose. So, she could know about it, but should there be anything to cause her to remember, then fail.
But then again, you are more aware of your relationship with her, and such. I'm pretty sure you'll make a good decision. But yeah, that's my two bits, and I must say... I can't applaud you enough for being so cool-headed about it and wanting to talk it out. That's by far the best thing you could do, in my opinion.
Anyway, best of luck with that, TimJing; I sincerely mean it. I know we all have your back 100% of the way. (at least I know I do... hahaha)