In the past, when your organization used multiple membership levels (example: General Membership, Gold Membership, Platinum Membership) that meant when someone renewed online at a higher level, a new remembership was created rather than upgrading and renewing the old membership. This is no longer the case! To make the most of this new feature we've started using the automated membership reminder email feature in conjunction with this new enhancement.
Note: We use Drupal 6 and CiviCRM 3.4 on this site.
Step 1: Create a reminder email message for EACH membership level here: http://yoursite.org/civicrm/admin/messageTemplates
Step 2: (optional) Use the Path redirect module to make pretty links for renewals that work well in a plain text format. Why this module? Standard Drupal aliases tend to not work well with CiviCRM's paths. For example: http://yoursite.org/renew can redirect to https://yoursite.org/civicrm/contribute/transact/?reset=1&id=1
Step 3: Include in the reminder message a link to renew at their existing membership level, and a link to up-sell them at the next level. Here's an example:
You can renew your Sponsor membership today online or by calling (202) 939-2675. Please consider increasing your level of support this year by committing to USNC at the next level of membership: Patron with your online payment or by calling (202) 939-2675
Step 4: Pass along a URL parameter (I call mine 'membershipbutton') that corresponds to the radio button id of the membership level they wish to renew. The URL might look like this: https://yoursite.org/civicrm/contribute/transact/?reset=1&id=1&membershi...
If everything goes according to plan (cross-fingers) we will see people clicking the upsell links in their emails, being redirected to the renewal page, having their membership level pre-selected, and the membership upsell renewed with continuity for their membership record. You can see some of these links in action at my client US National Committee for UN Women: