Bookmarks Variables with Bookmarks

When a bookmark is created, it saves the variables that were entered to create the query.

Is there anyway of telling it to reset the variables to the default values?

I have a number of reports where there is a date range that has its default values populated by a customer exit. The date range is generally relative to the date on which the report is run (eg will run for the last 6 weeks). If they change the navigation state, and bookmark so that they can return to this, I want the variables for the date range to use the default values when they return to it.

Is there a way that I can do this?

Thanks in advance for any assistance.