RENEW a third-party SSL Certificate for use with WebVPN on an ASA

I used this link to create a CSR request and install a third-party SSL certificate on my ASA 5510 for WebVPN.

http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a00808b3cff.shtml

This removed the security popup when users hit the url to use the VPN, and works quite nicely.  

Now, the SSL cert is up for renewal, how do I create a renewal request from the ASA for the certificate?  The above link shows doing an ADD for a new one, Ijust want to renew the existing one...

TIA