I'd examine vibe, angle on approach, opener, topics, and smoothness vs. roughness.
Go for slightly more nervous/excited vibe. Make your approach angle more "just happened to see her; noticed her for a moment; then approached." Make opener something a random (confident) guy might use if he sees a girl who really floors him. Pick topics that are more normal and less game-y. Keep rough edges / don't be too smooth.
I don't know exactly what your approach looks like. But most guys who do a lot of approaching after a while fall into habits, where they have their approach and dialogue down pat, and it starts to come across like a script the guy has memorized. Might be fun/cool, but he seems a lot less nervous/excited than a normal guy would be on approach, a lot more polished, has to think/pause less, and comes up with a little too much clever stuff for it to be "on the fly."
It's a "seasoned veteran problem" - coming down from the place where you have it down pat/super smooth, and adding in that roughness and naturalness again she'd expect from a guy who doesn't "usually do this" but just decided to approach.