How to save your work...and your data!
When you want to save not only a version of your canvas but also what you data looked like at a specific time, then you can use Data snapshots.
In order for data snapshots to work you must have enabled either Static or Scheduled query updates. See the following page for more info:
Then when you turn on static caching a version will be saved, or when you re-run all cells.
Then a new data snapshot will be created every time your queries update according to your schedule. If you re-run all cells a new snapshot will also be generated.
You can click into any version with a snapshot to see what the data and the canvas looked like at that time.
By restoring an old data snapshot you are essentially replacing the cached data that will be used in the canvas. You can always update the queries by selecting 'Run all' from the caching menu.