Button on a form to run a script?

Button on a form to run a script?

I have a series of data input fields, visible calculated fields and fields that show as set variable results. I want the script to run after the user has completed inputting the data and this is of course easy to do as an 'on user input' on the last field. However in many instances the user will see the results and wish to recalculate after modifying one of the input fields. I need something like a RECALCULATE button at the bottom of the page. Any ideas?