List built with javascript is cleared by the back button

[admin]

I have an HTML form that collects a lot of data. Seven of the fields are drop-down lists that are built dynamically with javascript. The problem occurs when a user hits the back button to return to the HTML form and edit data. The form retains the user entered data for all of the fields except the list built from javascript. The lists revert back to the original list if I use onLoad in the body tag or if I use onFocus at the form element itself. I am not permitted to use cookies on this site so I cannot store the data locally. My only success has been to write all of the data to ASP session variables, default the HTML form values to these session variables and then prevent the browser from caching the HTML form. The problem is that with all of the data I am passing, this has been a resource hog. Can anyone think of a way that I can build these lists dynamically yet preserve the user entered value if they hit the back button?