Reply To: Ajax Pro Search layout change

That should work, I was able to test it on our local server. Try this variation maybe placing to the functions.php file in your theme directory:

add_action('wp_footer', 'asp_add_script_to_footer', 999999);
function asp_add_script_to_footer() {
	?>
	<script>
	jQuery(function($){
		$('.asp_option_label').each(function(){
			if ( $(this).text().trim() == 'Strand E – Morality and Justice' ) {
				$(this).addClass('new-filter');
			}
		});
	});
	<script>
	<?php
}

If no luck, then you can try the filters templating feature. That lets you make changes to the filters layout without losing them on plugin updaes.