In reply to SiWood:
Are you trying to replace tape seam sealing, or to repair a split bonded seam?
For the former, remove to old tape and replace with new iron-on seam seal tape.
For the latter, sewing is likely to be the most robust repair. The origianl seam is likely to be a thermally-activated glue tape; rather like iron-on seam seal tape, only just consisting of the glue layer.