Backfilling
Not to be confused with the similarly named BackTracking, backfilling allows you to run your triggers across previous times in history.
This is particularly useful when you've introduced new types of reports or analytics, as they allow you to generate them for times in the past, not just for times in the future.
To backfill, you change the last line of your file. Instead of calling…
arditrigger.Start('servername','sitename')
…you instead call…
arditrigger.Backfill('servername','sitename',start,end)
Making sure that the start and end times are in UTC.