First off, you don't need javascript to do this.
Let's say we're posting the form on page 1 to the form on page 2. We'll have a var something like this:
$_POST['SearchType']
that is a radio button, that can be, let's say, yes,no or maybe. When we build the new buttons, we need to test it, something like this:
<?php
$choices = array("yes","no","maybe");
foreach($choices as $choice){
print '<input type="radio" name="SearchType" value="'.$choice.'"';
if ($POST['SearchType']==$choice) print ' checked';
print '>';
}
?>
You need to do that for each of your radio buttons. This lets you do the work in PHP and NOT create another layer of javascript, and will work with non-js enabled browsers (if you write code for gov't offices and such, you never know what they're NOT gonna have this week.)