When setting up a recurring report, sites have to be added to the "included" list. If a new site is built, by default it is not included in the report. Reports have to manually be edited to include any new sites.
Further more, if sites were able to be marked "active" or "inactive" it would prevent unnecessary sites from being included in the data.
This would be a nice addition, I am pulling reports and find I am missing sites because they were not added, and I was not aware they there added. Now I have to go back each time and check to see if there were additions. When I have reports run on a schedule it becomes even more an issue.