Pivot Table filtering in templates

I have an Excel template file with two sheets. One is a pivot table, the other is the source sheet for the pivot data.

If I filter the pivot table, clear out all values from the source data sheet, and then refresh all data; then, any specific filters I applied are still present in the pivot table sheet (even though the filtered values no longer exist in source!). Also, If I close the worksheet, add new data to the source, then, the old filters are still saved in the pivot table.

Two questions:

1) Why/How does this work? ;

and

2) Can I manually add pivot filters for items which aren't in the source data? For example, if my source sheet only lists DOGS in an "Animal" column, can I add a filter for CATS in a pivot table based on that source sheet
Thanks!

UPDATE: Sorry, it looks like the Pivot "Filter" field itself does not save previous filters. But, any data in the Row and Column Labels will still be present, and any filtering applied to those two fields will be saved even if the source is cleared.

Try this:

Right-Click on a Pivot Table cell
-Pivot Table Options...Data...
--Number of items to retain per field:
->Change from Automatic to None

Does that help?