AC blows air fine, but doesn't get cool

I recently had to get my car's 3-year-old battery replaced after not using it for 12 days, since I was on vacation out of state. One thing I noticed both before and after I got the battery replaced, however, is that the AC doesn't blow cool air. If I turn all the settings up it'll blow air without a problem, it just doesn't get cool. And considering I live in Florida, this is even more difficult to endure.

I brought this up to a friend who had a similar issue with his car a few months back, and he suggested recharging the AC, something I've absolutely no idea how to do. I've heard it's just a temporary fix, but he said that after he recharged his car's AC, it worked (and has continued to work) like a champ.

Could that be all I need to do, or is it likely that I'd have to put the AC through full service (which I hear is expensive)?

My car is a 2004 Pontiac Grand Prix.

EDIT: I appreciate all the responses! I'll be dropping my car off at a local shop I usually go to tomorrow to diagnose what's amiss. Really hope it's nothing more than a leak, because I've heard how expensive AC repairs can be, and if it's something that's going to cost over $1000 then I might honestly consider getting a different car, since I've already dumped nearly $800 of maintenance into it so far this year.

EDIT 2: Brought it to a shop and they said the compressor would need to be replaced, along with some other work. They quoted me at just under $1500. That's more than I'll probably get for selling or trading the car in, so as far as I'm concerned, it's days with me are numbered.