Plugin: Genesis Single Post Navigation -- Customize parameters for "next post link" -- add this to functions.php of your child theme

gistfile1.aw

<?php

add_filter( 'gspn_next_post_link', 'custom_gspn_next_link' );
/**
 * Genesis Single Post Navigation: Add custom filters for "next post link"
 */
function custom_gspn_next_link() {

	$args = array (
		'format'                => '%link',     // Change link format (default: %link)
		'link'                  => '&laquo;',   // Change link string (default: &laquo;)
		'in_same_cat'           => FALSE,       // Apply only to same category (default: FALSE)
		'excluded_categories'   => ''           // Exclude categories (default: empty)
	);

	next_post_link( $args['format'], $args['link'], $args['in_same_cat'], $args['excluded_categories'] );
}