Does anyone know how to change a workflow for a part that exists in the vault?

During kickoff of EPDM implementation, we used a very simple "Migration" workflow to get every part from our WPDM vault migrated to EPDM. I now want to use new workflows for some parts in different folders. I have my new workflow properties set up correctly such that new parts checked in adopt the right workflow but I can't figure out how to change a workflow for existing parts. Any ideas besides destroying and checking in?

Thanks