How to recover jam that is too liquid? I made redcurrant jam some months ago, with sugar/pectin-mix. I used the appropriate amount. However, the mix was very old (+5 years). I tried it anyway. The jam turned out like a syrup, it is very liquid, but the taste is fine.

If I heat my jam/syrup and I add some new-bought pectin, would it turn out fine?
I have done this before and it has worked for me. It should work, but if it doesn't, I know what will. My aunt sold Jam for a while and when the pectin didn't work she reheated and added a small amount of gelatin, I helped her stir it in, and that was the final fix for her bad mix.