I have talked with a colleague about this and there is a better way to do it. You should select the HTMLEditor instance on the page and delete it first, then add in a new one.
For the new one make sure to name it ContentValue. After you are configure it and create it you will need to update the last parameter for it. In the code view you should see the code that looks like this:
$WARichTextEditor_1 = CreateRichTextEditor ("ContentValue", "../HTMLEditor/", "713px", "400px", "Custom", "../custom/contents_update_ContentValue1.php", "");
in this code replace the "" at the end with this:
"".($totalRows_HistoryUpdate > 0)?((isset($_POST['ContentValue']) && $row_HistoryUpdate['HistoryValue'] != $_POST['ContentValue'])?$row_WADAContents['ContentValue']:$row_HistoryUpdate['HistoryValue']):$row_WADAContents['ContentValue'] .""
This should get it working for you, let us know if you have any other problems with it.