data assist search stores the original search in a session variable, if the page is reloaded without triggering the search behavior, it will automatically use the search stored in the session.
on the data assist support page, there is a tutorial for "Sorting by column links" in the solution recipes section that can help you get started.
dataassist/
you could use the same principal with a select list of columns instead of column links, just set the forms method to GET instead of POST, and name the select list "sort"