This covers upgrading from any version prior to 7.x-2.1beta1

7.x-2.1beta1 is a complete refactoring of the code of this module.  Many 
functions where renamed and many files were renamed in order to adhere to
Drupal.org coding standards.  This renaming could or could not affect your
existing rules.  Therefore, in order to upgrade your module you
will have to do a couple of steps.  This is the safest route for upgrading.

1. Export all rules you may have built on this module.
2. Disable and uninstall CRE 
   If you use drush:
   > drush dis -y commerce_rules_extra
   > drush pm-uninstall -y commerce_rules_extra
3. Disable all Rules that are built on this module (should have happened with #1).
4. Delete all Rules that are built on this module (if they exist anywhere 
   in the Rules UI)
5. Delete the existing module files and folder.
6. Reinstall CRE with the latest code.
7. Rebuild rules from #2.  You likely cannot restore from code as function names
   changed due to the clean up of the coding in the module to adhere to Drupal
   standards.

You may choose to not disable, export, delete, and restore your rules but you
must complete #4 and #5 or you will cause Drupal to crash - the old module files
must be deleted.