on the confirm page, add a set session value for each form element.
Open the server behaviors panel and click the plus button. Select eCart -> General -> Set Session Value
set the trigger to any form post.
Click the lightning bolt next to value and select one of the checkout form elements. Set the name of the session to the same as the name of the selected form element.
on the checkout page, select each form element, on the property inspector, click the lightning bolt next to initial value and select the corresponding session variable.