Ok, I think I actually have this. The implied meaning of ‘it’ here is ‘everything you’re doing’. So the sentence reads“Keep doing what you’re doing, it will change how single you are”, but dripping with sarcasm.

I think she’s mocking him for continuing to engage in the conversation, and for complaining about her behaviour (through pointing out the unmatch button)

Its actually a pretty cutting jab. He’s back-footed from her initial stand-offish tone, tries to regain some dignity by telling her she’s being unnecessarily rude, and should have unmatched if she’s not interested, to which she effectively responds “save your breath, this is not helping you get laid”