software

I inherited the task of rolling workbooks over to accept data for 2006. This
is a general idea of how things are set up: 5 employees each have a workbook,
which lists their daily tasks. The amount of time spent on each task and
number completed are entered. Calculations are made to determine average time
per each unit. The sheet tabs are labled by the week's date, for the entire
year i.e. (Dec26-30)
The totals in the above sheets roll to separate workbook which totals the
combined totals for the 5 employees. Which in turn rolls into an additional
workbook that combines it monthly.
Clearing the data and saving the employee workbooks with the new dates on
the sheet tabs causes all the formulas in the in the quot;rollupquot; workbooks to
display quot;refquot;
How can I set up the new workbooks and worksheets to allow easy portability
into a new year?