I just cleaned out my pumps that had been sitting a year still in half full jugs.  Soaked for a bit in alcohol then pumped some thru a few times.  Had to take a toothpick to the hardener's spout to get out a plug, but then they worked fine.  Just pumped a shot or two thru each and threw it away before using for real.  Clean them now and don't worry. Put the lids back on the jugs.  The resin might crystallize a bit, but soak the jug in hot water and it comes back.  It won't last forever, but should go a couple of years or so.

It's been over 2 years since I finished my build and I stored the epoxy  on a shelf in the shop. Occasionally I'll have a project that needs some epoxy and i's fine, I haven't cleaned the pumps and I should take the time to do that.