to keep you values alive, place each in a variable when submitting and then set them as selected when rebuilding the form
here is the code to keep them alive
$items can be an array or a database call dataset
$item is the item choosen by the last go around - this is for one item....to use this for a list of items either change the name for each item or use an array
$num_elements=count($items);
for($x=0;$x<$num_elements;$x++){
if ($myItem==$items[$x]){
echo "";
}else{
echo "";
}//close if then
}//close for loop