My Old Best Friend seems to want to get close to me again.

I' was always close with someone in my year, but after being good friends for around a year we became best friends. We'd do everything together, go places, go to lunch, laugh and just generally have fun. After around a year of this, he just stopped being so close ot me and eventually ditched me for another group of people who are into sports and other things like that. I didn't really care much for it as I try not to get attached to people and I went with another group of friends for a while.
In the past week he seems to be trying to get closer to me again, snap chatting me, asking me what movies he should watch, debating whether or not he soul come down to see me and some other people and I'm just confused and on't know how to react. Help somebody please.

It sounds like he ditched you when he found something he thought was better and now he is either regretting it or they ditched him. Ultimately you have the option of taking him back knowing he will probably do the same again or stopping him before he starts.

lol, I've been best mates with him since September.

I would still remain cautious, I have known many leeches in life who will abandon people at the first sign of finding something 'better' because they don't actually care about the individual, only about their interests.