Upgrade process does not erase your data. Don`t be afraid to upgrade.
Get the latest version files from your account area My Downloadable Products section.
Disable Compilation mode from System > Tools > Compilation admin page.
Copy contents of "step_1" folder to your Magento directory so that the app folder is merged with the app folder of your site, skin merged with skin and so on.
After step_1 files have been copied, copy contents of "step_2" folder to your Magento directory.
Flush Magento cache storage from System > Cache Management page.
If you are using Compilation mode on your site you need to Run Compilation Process from System > Tools > Compilation page.