*applause* for the Brother who is already thinking about APO post-graduation! Of course you can remain involved and stay active.
www.apo.org
Our national website has a list of all the Alumni Chapters. I'm trying to get into one myself.
Also, Life membership is only $50 up to a year after you graduate, so that is not a bad investment. Not only will you become a life member (you're a life member anyway since pledging APO is a life-time committment), it also means that you'll be recognized at all events our Organization holds and you get some other perks too.
I'm sure some other Brothers will have some ideas to add on this topic...