Hi Barb,
I believe the earlier responses were correct. Provided you still have transactions on file, the customer's statistics can be recalculated. If you've purged history, there might not be this year's or last year's transactions. There are date ranges for the period start/end, current year start/end and prior year start/end. You can play with those date ranges and run the function repeatedly. For example, you could set your period range to be September, 2009. You can selectively recalculate a particular set of statistics. A screenshot would be easier.
The short answer is that it should work for you.
Thanks,
Bob.