It looks like that you want to compare the performance between two model versions.
At the moment, it is not possible to "save as" or predict using a non-published version excepted with the quick test button.
We are working at the moment to improve model lifecycle capabilities.
In particular, supporting more model versions, being able to predict on a non published version, or rollback to a previews version (so you can publish a new version, check the performance and rollback if not satisfactory)
This is planned for Q1 next year.
In the meantime, the only option is unfortunately to rebuild a new model.