First draft of the idea, on a graph that was archived and restarted 3 times over the years:
This is actually live already at the graph.beeminder.com version of the graphs if you want to experiment. You just need to add your own #ARCHIVE tags to mark when the archivings happened.
You could call it a feature that PPRs are as annoying and ugly and in your face as possible. All the more incentive to hurry and add the real data that will make them self-destruct!