You don't expect him to take down his profile after one good date, do you? Why would he? It's a little too soon to declare you "the one." Did you take down your profile on the site?
He asked you out again, so obviously he likes you. But unless you two agreed to be exclusive after one date, there's no reason for either of you to take yourself off the market. Dating isn't like Netflix DVDs; there's no limit to how many you can have at one time. He might be seeing several women at once, as is his right-- and yours. It's called hedging your bets, and there's nothing wrong with it this early in your relationship.
So don't take it personally--the fact that he's still active on the site has nothing to do with how he feels about you. It's all about playing the odds and having several irons in the fire at once. If you two go out for a while and start to get serious, then you can worry about whether or not he's still looking.
For now, just enjoy your time together and don't concern yourself with whether or not he wants someone better. Who knows, maybe you're the "better" to someone else he stopped dating. And don't turn down dates from other guys. It's much too soon to settle for one, no matter how much you like him.