For customers on Business or Enterprise plans, CloudFlare offers the ability to upload your own SSL certificates to have these presented to visitors as they access your website. This is especially helpful for Extended Validation certificates so that your visitors will get your information in the "green address bar" presented in your visitor's web browser.
Keeping your SSL certificates up to date is an important security practice to ensure that customer web browsers continue to interpret your SSL certificate as valid. Every SSL certificate has an expiration date. As a best practice, be sure to regularly acquire updated SSL certificates from your certificate vendor as you approach the SSL certificate expiration date. Once acquired, these certificates should then be uploaded to CloudFlare.
For customers who require PCI Compliance for your web properties, this is an important and required step to remain in compliance for this particular PCI compliance requirement (3.6.4 in the PCI DSS 2.0 specification).
Updating your SSL certificates can be done on the "Custom SSL" options screen for your domain name by using the "Update" option as shown below: