I used to always run into this problem. Sometimes I'd freeze it but then I'd forget it was in there and open another can.Does it work well as a thickener?
My wife bought some dehydrated tomato powder like this:
It really works great and is super convenient.
Seems to work pretty good. I used to reconstitute it into tomato paste form and then add it, but now I just add the powder and adjust the other liquid content if necessary