Strategies for Keeping the Big Bad Alive in a Campaign

You were looking forward to an antagonist for the PCs that would last a few months.  You had a plan to integrate him into two of the PCs' backstories and for a climactic battle on a volcanic rock.  But the PCs were smart and found a way to kill your big bad earlier than you wanted.  In this episode Jeremy discusses what you should do next and some strategies to keep it from happening in the future.