Do you mean https://en.wikipedia.org/wiki/Persistent_data_structure or something more specific for this case? It's known how to only incur an O(1) cost in time and space for making a data structure persistent. So then you just need to keep a reference to all past versions of the data structure you might ever want to undo back to.

EDIT: actually reading the wiki more carefully, I think they were talking about making a BST persistent specifically rather than any data structure. In that case looking at implementations such as rrb-vectors might be more interesting: https://github.com/clojure/core.rrb-vector