Sorry, DBlank is correct. Each report is a separate entity, and would needs it selection information updated. Since all of the reports are binary files, you need to go into each one and modify it.
If you gathered your information via a stored proc, you would only need to update the stored proc script, Crystal wouldn't care that the reason for the data coming back is different as long as the structure hasn't changed.
You would still need to modify the stored procs, but that could much more of a cut and paste type solution rather than opening 100 reports.
Sorry, we can't be of more help