As long as your default information doesn't include number data you can use this method which will clear all the numeric data, after you have saved it as detailed by canarieslover
*Press F5 to display the "Go To" box.
Select the "Special" button.
Choose the "Constants" button and remove the ticks from the Text, Logicals, and Error boxes.
"Numbers" should be the ONLY box ticked.
When you click "OK", every numeric cell across the spreadsheet will be selected.
Now manually press "Delete" to delete the values.
If you have text in the spreadsheet aswell, you would just de-select the "Numbers" option and select the "Text" option*
I would go with Canarieslover's solution. The main consideration is the Naming of the saved File, for which I have a suggestion.
If the main Spread Sheet is called, for example, "Group Sales-Daily" I would rename your File "Group Sales-2011.04.21" or something similar. If you use the 'Year.Month.Day' format. When they get to the other end, all the Spreadsheets file themselves in date order throughout the year.