Can my syrupy jelly be processed again to make it set, or do I need to start over? I have a blackberry watermelon jelly that I made and it didn't set up.  I waited about 3 weeks for it to set up and then reprocessed it, adding more pectin.  I added 1 1/2 packages of pectin (it was a large batch) and it still didn't set up.  I've looked on-line but can't find anyone who's actually reprocessed a second time.  People have asked but no one has done it to answer.

Can I reprocess it or do I just have to resign myself to having syrup?
You can use a chilled plate to test your batch before canning it next time. Pectin does not firms up with time, just temperature. 

I would suspect that the watermelon juice has made your jelly too dilute, and you'll need to boil your jelly down further.