I was reading something on NPR.org about the reality of our ability to hold on to friends, keep track of what is going on in their lives, and generally actually care about them. The article suggests that we are only able to keep track of 150 friends, so if you have 1353 friends on facebook, don't believe it. It's not possible.
The article has an interesting parallel to the appropriate size of a management structure within a company (i.e the factory example, if you will). But it's pretty easy to figure out- too many people means it is too hard to keep track of the details from the people in your life.
That being said, legitimately keeping up with 150 people would actually be pretty impressive. My advice? Start with a few old friends that you haven't reached out to in a bit. Drop a line. Tell them you miss them, the fun you used to have together and that you love them. It will be worth it.