rushing as a sophomore

It's a lie that some sororities don't take upperclassmen. Every house takes upperclassmen but you will have to be a very polished and outgoing PNM if you're looking to get a bid from a "top" house. Overall with your high college GPA and your involvement you'll definitely have a decent amount of options.

As a sophomore you will be looked at apart from the freshmen, which is a good thing. You have every chance to do well.

IF you are a quality sophomore ( very good to excellent gpa and solid extracurricular activities, be it involvement in your church, sports, or charity), the doors are wide open. Sophomores/ upperclassmen have their own quota. This quota is in addition to the PNM quota that is figured out depending on the numbers of girls who rush. Houses can chose to put sophomores in the upperclassmen quota or in the regular PNM spot. Any house would love to get quality sophomores because they are super helpful to their freshman class (they know how to balance schoolwork already and know the freshman core classes). Some houses take juniors, too.

Fear not. ALL the houses, even the snooty so-called "old row" (a misnomer) sororities take sophomores. Be sure you have excellent grades, a sterling reputation, and evidence that you have been involved in a few organizations on campus. If you haven't been, start right this minute.
Polish your wardrobe and appearance.
And GET RECS. Yes, to every group. More than one would not hurt a bit. You want attention called to you and how you would be a coup to pledge.
Be prepared to explain multiple times at each house why a prize such as you did not rush her freshman year. Do it patiently and sweetly.
Baby, you are gonna go out there a rushee, and come back a STAR!