I have a 9oz. 5min Kwik Bond epoxy set (Hobby People) and Part A has gotten hard, even though Part B is just fine. It is not all that old, maybe 5 months. I used a small portion for a project then put the caps back on and the bottles in the bag and set it on the shelf until needed again. Is there any way to soften up or hopefully liquify Part A back to its original syrupy consistency? How does everyone avoid spending $10 ($8 plus tax plus gas...) every time they need to glue in a firewall or some other teeny-tiny job?

Thanks in advance...