Prompted to give an answer by @apaul, I thought I'd give a woman's perspective here :)

As per my [answer over at Workplace.SE on wandering eyes](https://workplace.stackexchange.com/questions/86261/talking-to-colleague-with-short-skirt-how-do-i-not-come-off-as-a-creep/86286#86286), most women are fairly used to the occasional involuntary glance at our chests from guys.  It happens.  However, once it reaches a point of "can't take your eyes off" then it rapidly jumps into creepy territory.

Unless your player is wearing something that is blatantly inappropriate for wearing on out in public, then it really is your problem to deal with.  Try to focus on her face when you're talking to her (yes, I know you will have involuntary glances from time to time), but as long as it's clear you're trying to do the right then she will likely be not overly offended.

With your question "Should I apologise?", the answer is no, let it go.  It's just going to get awkward.  Take the fact that she signed up again as a positive indication that she wants to continue and wasn't entirely creeped out.  Yet.  You may find that this time around she will take it on herself to wear something less revealing, but even if she doesn't, the onus is on _you_ to control _your_ behaviour, not hers.