I suppose it depends on what kind of lube was left in it, but I'd just set it on a cookie sheet in front of a heater vent somewhere and let it warm up and (hopefully) run out. Definitely no propane torches or the like directly on the lube -- most lubes will ignite, and there are rubber parts inside you don't want to damage. Gently warming the whole thing will either liquefy the lube or at least soften it to where it can be scraped out with plastic tools (no metal, the castings scratch easily). Quite frankly, I wouldn't worry about mixing with new lube and lubing a batch of bullets if it can be softened to a point where it flows through the system.
Just my 4 cents worth... inflation, y'know.
mike