I can disconfirm this. I tried for 4 payment days straight after being declined. Nothing happened.
Yes, looks like you can only gain affection the first payment day. I revised the walkthrough to include day 2 so people don't have trouble getting her hair later. So now it has all the times you can get her affection. You don't seem to be able to get affection from her anywhere after you miss these chances so you will have to start a new game.