Dynamically Reference Offline Workbook/worksheet
 

I have a workbook that has a vlookup cell reference to another workbook
(stored in sharepoint), in a column of cells. It looks similar to this:

=VLOOKUP(A650,'http://na2.mycompany.com/teams/IPGAM/IPGAM%20Documents/030%20Metrics%20and%20Reporting/00%20metrics/[EPR_Dashboard_09032007.xls]Audit'!$B$11:$C$649,2,FALSE)

The above works just fine. However, every week, I must change the file name
(the [EPR_Dashboard_09032007.xls] portion of the formula. Up to now, I have
simply been do a find/replace, every week, but thought, "what if I could
simply have a cell somewhere in the workbook where I could change the
filename I am point to, and it would automatically change the formulas in the
thousands of cells I am doing the vlookup in. I have monkeyed around with
INDIRECT, etc, but am probably not doing it right, nor am I even sure if that
is the way to go about it.

Ideas?