Well, since you said "semester" . . . I'm going to assume you're a broke-ass college student.
That couch, obviously, isn't exactly a pinnacle of the furniture maker's craft. Just glue, clamp, and screw some additional support to it (and the rest of the sections while you're at it) using something besides freakin'
plywood. You can get hardwood 1 X 2 stock at any home center. Some little 'L' brackets where the sister piece abuts the front-to-back supports will make it fairly bulletproof, fat ass notwithstanding. :laugh:
The springs just reattach. It's a little tricky from that angle, because they're stapled down to the frame from the other side, before the batting goes in. I'd suggest attaching them to the sister piece instead.
~Boar
Oh, and you can make the whole thing a helluva lot sturdier if you tie the springs off better while you've got it open:
Different kind of springs, but you get the idea.
~Boar