In most situations you will not require us to generate a new Certificate Signing Request (CSR) to renew an SSL certificate because you can simply use the one we generated for you when you first purchased the certificate. However, we are finding that many SSL certificate issuers are now requesting that a new CSR be generated for each renewal. Therefore, we advise opening a ticket with us a few days before your certificate expires so that we can generate a new CSR and you can then get your certificate renewal purchased.
The reason that many certificate issuers will ask you to generate a new key pair and CSR to request a certificate renewal is because by renewing your public key along with the certificate you help to protect against the risk of the cryptographic key being compromised by a sustained computational attack over many years and maintain improved security for your transactions. You should check with your specific SSL certificate issuer to find out what their policy is with regards to renewals.