You've already told him once, and it didn't change your relationship. He didn't declare his romantic interest in return. Was this because he genuinely didn't hear you or because he didn't share your romantic feelings? I suspect it was the latter and you may not want to admit it to yourself.
You need to be honest with yourself about whether this is a one-sided or two-sided love interest. Does he provide any signals to you that he is attracted to you sexually? (For example, he leans in, stands close, touches you a lot, gazes at you, listens like no one else is in the room, etc.)
If you are confused, have a conversation with him about the mixed signals you're getting when the time is right. Alternatively, introduce the topic by asking if he recalls that time when you confessed a crush on him. Then inquire whether he could ever picture a situation in which you two were more than just friends. You don't have to pour out your emotions because you're asking him how HE feels. You've already revealed your crush on him. He has certainly noticed your goo-goo eyes at him. This will get the issue out in the open.
It's better to talk about this "elephant in the room" between you than ignore that it's there. If he rejects you, it will no doubt hurt, but you will live through it. We have all been through rejection. It doesn't mean you are defective. It can simply mean you're not the right person for him right now, or logically you're great together but he just doesn't feel sexual chemistry. It's hard to figure out what lights a fire under even our own hearts sometimes. Don't take it personally, and certainly don't undervalue your friendship. Have that conversation so you can either start dating or start processing your feelings and move on emotionally.