Should I give up on him or keep trying?

I have a crush on the boy who I've grown up with next door. He is also a year and a half younger than me. I'm pretty sure he liked me when he was about 6 or 7, and I don't know if he still does or not. Sometimes he acts like he does, but sometimes it's really hard to tell. Over the years we have grown apart a little bit, but still managed to be friendly towards each other, especially since I was good friends with his sister. But last September our families hit a rough patch and even though we apologized and they forgave us, things haven't been the same. We don't even say hi to each other anymore, and I only talk to his sister when I see her at church or outside every now and then. It makes me sad looking at old pictures and realizing how close we were. Also he works at this camp that I'm helping out at, and my friend says that he stares at me a lot. But when I rode past him on my bike, he seemed to avoid looking at me. Last week he also squirted a water gun in my face but smiled when I turned to look at him. But I saw him again on his bike the other night, and I said "Hi" but he didn't even bother to turn his head towards me or reply. I'm pretty sure he heard me. Yesterday I started hanging out with his sister and the three of us ended up playing basketball together, and things felt a little awkward but after a while, normal again. He smiled at me a few times and even called me by my nickname again. When I left, he said "See yaa" and smiled as I was leaving. Today I passed by him and waved and he seemed to give me a shy half smile before turning away again. I want to ask them to play basketball again or something, but I'm worried that it will feel awkward and weird for us again. What should I do to keep our friendship from fading away again? And does he want to be my friend again?