Currently you can import a workspace from a JSON file which is nice as you don't need to setup the whole service and train it. But you can't upload to an existing workspace. I am looking for a way where you can override existing one so you don't have to change credentials in your app, and delete the old workspace. In this way you can reduce some manual steps.
As you have planned for this idea: https://ibm-watson.ideas.aha.io/ideas/WCS-I-13 i think there would be no problem with overriding because you can then revert back to older versions as well.