While this is not currently a feature set, I will change this posting to an 'Idea' for future product enhancements.
Sorry, there is a point where we do recycle training history-- after which time, this information is no longer available.
I really, really need this functionality too! It's a pain to sift through previous trainings and make copies instead of being able to choose a base template with every new training. Thanks!
@itomlinson I am sorry that I cannot comment on the development of this feature. I can say however, that there will be some big changes to the GoToTraining and Webinar platforms in the year 2019, so stay tuned in the coming months for additional information.