If the Domain is still within the 29 Day Grace Period,
To Renew your Domain Registration (not your web hosting account):
You can do this by logging into your Online Account Manager at:
http://www.hostingcheck.com/billing/
Then, Click "Domains" from the Menu,
Then, Click "My Domains" from the Drop Down Menu,
Then, Click on the "Renew" Button next to the Domain Name that you want to Renew.
Follow the instructions from there.