Yes, If you have changed e-mail address and therefore not received a reminder then you will need to log in to your account area to renew the certificate. Your certificate should contain the extra amount of time. If it does not, please submit a support ticket.
To renew your certificate please log into your Comodo account. You may do so off of any of our sites such as: InstantSSL.com . Under "My Account Areas" there will be a selection for "SSL Certificates". If you are having trouble locating this, please either give us a call (1-888-COMODO1 -- US: +1.888.266.6361) or submit a support ticket through http://support.comodo.com