You should avoid using the CSR generated during the initial certificate activation, as this is not secure and can compromise your SSL certificate usage. Your hosting company should assist you with a repeated CSR code generation. In case you are able to generate a new CSR yourself, please check out our CSR generation instructions.
Pay attention to the fact that you will need to go through validation for the Renewal certificate once again, that's why we recommend that you renew your certificate at least two weeks prior to its expiration date.