your form uses the get method.
in this code:
<?php echo(isset($_POST['keywordfilter'])?$_POST['keywordfilter']:""); ?>
you referencing a form element from the post method.
it should be:
<?php echo(isset($_GET['keywordfilter'])?$_GET['keywordfilter']:""); ?>
your form includes the following fields:
caption, keywordfilter, companyname, contactfirstname, contactlastname, city, fldstate, interestid
you will need an echo statement for each one.