How to keep the states of a dynamically-created checkbox list after validation

<ul>
<li><label for="document86" ><input type="checkbox" id="document86" name="requested_documents[]"  value="assets/files/downloads/InternetRetailer.CVN.pdf"  />86-CARD VERIFICATION NUMBERS SERVE OFFLINE WORLD, BUT ARE THEY A REMEDY FOR INTERNET CARD FRAUD?</label></li>
<div>86</div><div>85</div>
<li><label for="document85" ><input type="checkbox" id="document85" name="requested_documents[]"  value="assets/files/downloads/ChipCardFraud_WP_FINAL.pdf"  />85-PAYMENT CARD FRAUD IN A CHIP CARD WORLD</label></li>
<div>85</div><div>85</div>	
<li><label for="document84" ><input type="checkbox" id="document84" name="requested_documents[]"  value="assets/files/downloads/JECM_The_Fraud_Management_Lifecycle.pdf"  />84-THE FRAUD MANAGEMENT LIFECYCLE® THEORY</label></li>
<div>84</div><div>85</div>
</ul>

<?php
function regDocsMenu(&$fields, &$templates)
{
	global $modx; // Access to DocumentParser
		//set up some array variable 
			$lines = array();
			$doclist = array();
			//check the URL for any query string vars for requested docs
			if (isset($_GET['docid'])) {
				$requested = $_GET['docid'];
			} else {
				$requested = 0;
			}
			//get the PDF document list from MODx text document
			$dittoOutput = $modx->runSnippet(
						"Ditto",
							array(
								"parents" => "49",
			       		"tpl" => "dittoDocListing",
								"showInMenuOnly" => "0",
								"display" => "all",
								"depth" => "3",
								"hideFolders" => "1",
								"showPublishedOnly" => "1",
								"hidePrivate" => "1"
			        )
			);
			//separate the lines of documents
					$lines = explode("|~", $dittoOutput);
					//loop through and grab file name and title
					foreach ($lines as $line) {	
						if (!empty($line) || $line != "") {
							$tempArr = explode("||", $line);
							array_push($doclist, $tempArr);
						}
					}
					
					//start the list of boxes
					$output = "<ul>";
					//add each document title and filename as label checkboxes
						foreach ($doclist as $item) {
							$output .= "\t<li><label for=\"document".$item[0]."\"><input type=\"checkbox\" id=\"document".$item[0]."\" name=\"requested_documents[]\" value=\"".trim($item[2])."\"";

							### This conditional statement is getting ignored
							//check to see if it is a selected document
							if( $item[0] == $requested ) {
								echo '**entered**';
								$output .= ' checked="checked"';
							}
							
							$output .= "/>".$item[0]."-".$item[1]."</label></li>\n";
							//$output .= '<div>'.$item[0].'</div>';
							//$output .='<div>'.$requested.'</div>';
						}
					$output .= "</ul>";
	## This allows setting some checkboxes onload. But doesn't hold the states
	//$fields['docsmenu'] = $output;
	
	## This doesn't allow checkboxes set onload, but does hold checkbox states
	$templates['tpl'] = str_replace( '[+docsmenu+]', $output, $templates['tpl']);
	return true;
}
?>							

//<?php
// skipped rest of code
   ### This conditional statement is getting ignored
   //check to see if it is a selected document
   if( $item[0] == $requested ) {
      //$output .= ' checked="checked"';
      $fields['requested_documents'][count($fields['requested_documents'])]=trim($item[2]);
   }
//skipped more code

//<?php
 if( count($post)==0 || $_POST['formid'] !=$modx->event->params['formid']) 
      $fields['requested_documents'][count($fields['requested_documents'])]=trim($item[2]);