Is it possible to regrind beans? Is it possible to regrind beans?

I have about half a bag of very nice coffee in a semi-coarse grind, and I want to use a brew method (Melitta cone) that's more appropriate for a medium-coarse grind.
This is a pretty good way to ruin a burr grinder. Worst case scenario, your burrs jam up so much that they can't spin and burn out your motor. A blade could help, but I'd argue that the inconsistent grind you'd get wouldn't be much of an improvement in cup quality anyway. Realistically you'd end up with some of your grinds unchanged, some at the size you want and some ground to dust. The different sized particles would extract unevenly and the dust is likely to clog the filter.

That said, you're not going to break a blade grinder by regrinding, so give it a shot and see how you like the results. At most you're out 20-50g of coffee.