Definitely try again... you lose nothing by going through rush/recruitment again. I know lots of people who joined GLOs as sophomores or juniors.
Think up some good questions ahead of time to ask when sisters put you on the spot. (The one question I hated hearing most during my rush was "Do you have any questions about XYZ?" I swore that I would never ask that question to a PNM

) A good question is "Why did you join a sorority?" (early rounds) or "What led you to choose XYZ?" (later rounds).
Also, do some research into the sororities on your campus. I would have been a lot more impressed by a PNM asking "What sorts of fundraisers do you do for Chaim Sheba?" than "What's your philanthropy program like?"
And know how to dress for each day... talk to your rho chi, and ask detailed questions (are jeans ok, should I wear a skirt, is this pantsuit ok for pref, etc).
Good luck, and be sure to come back and tell us your rush story... we love 'em