To begin with, I took the zipper stitching out, but only about halfway from the top edge down. The dress has a facing at the top, hiding the raw edges and the ends of the zipper tape. I had to remove a few of the topstitched stitches in order to free that edge.
I then realigned the zipper and pinned it into place. As you can see here, the zipper is moved in about ½". Then it gets tapered back into the original stitch line. I had to stitch the zipper into place using the invisible zipper techniques I explain in step 6 in the Invisible Zipper Tutorial
I then folded the facing back down, right sides together and serged the excess seam allowance off. (The black you see here is the ribbon for hanging)
This shows where I need to replace the topstitching. The picture is deceptive. The ends really do meet evenly at the top of the zipper!