just ignore that you've dated her way back when, if anything its just a fun, cute little anecdote that'll pop up at one point or the other, but yeah It's a good in and as mentioned by bansario it should eliminate any AA there might be, just take it easy, tease her a little and remember to kino and your well on your way to a solid game with this girl.
this kinda reminds me of another fun little game I've got going with one of my female friends, back when she was a virgin we would fool around and play fight (a great way to kino btw) and by the end of the night (if she wasn't sleeping over) she would have stolen a piece of my clothing or an accessory, and I would have taken one of hers, soon after she'd drop by again "to get her earring/armband or whatever, and we would make an evening out of it, then we'd steal another thing from each other and repeat the process, we still do it, and the playful "what piece of clothing can i take" game generally leaves us half undressed, and no, she isn't a virgin anymore
It's something that just accidentally happened without thinking about it, but I think ill find a way to work it into a gambit, because it's really fun and enjoyable a great way to kino and an easy way of getting girls out of their clothes, so you can try getting something like that going if you want to
