I didn't do anything very special with my unpopped kernels. I kept them separate from my stash of popping corn in their own jar, reasoning that these unpopped kernels were at least partially cooked already and would have a different cooking time than fresh kernels.
My favorite method for making popcorn is to throw the kernels in a paper bag and pop them in the microwave. Once I had collected enough unpopped kernels, I measured them out and popped them as usual. Cooking time was about a minute less than usual, but the kernels did indeed pop!
Well, all except for the inevitable teaspoon of grumpy kernels at the bottom of the bag. I decided that these had quite enough chances and tossed them in the trash.
Have you had success at re-popping unpopped popcorn?
(Image: Emma Christensen)