If you wish to retain the existing estimate pricing, use the original app version on which the existing estimate was created.
If you wish to see updated pricing for the existing estimate, you may upload to a later version. If you wish to retain that later version, save the estimate with a new name.
If the existing estimate does not load in a newer version, that means that the structure of the app has changed, and you can only upload the existing estimate to versions of the app prior to the structural change.