nuvi 1300 update from lower 49 to full North America

I recently purchased the nuMaps Lifetime North America for my nuvi 1300 which came with just the lower 49 installed. When I try to install, it says my maps are already up to date. I had installed the 2011.20 nuMaps OneTime lower 49 after I purchased the unit. Does anyone know how I can remove the lower 49 and install the full North America? Is there a way to make the unit think it has an older version?

Thanks!