Personally, I would leave it and knit the front to match. The end result would be a longer sweater, maybe a couple of inches?
Theoretically you could catch all the stitches in the two rows you want to work together, cut out the extra rows and graft it together, but I honestly think it would be quicker and less stressful to just knit the piece over again from that point on, if the extra rows cause a problem.
After all, we do like to knit, no? :teehee: