Extend the featured course summary

The featured course summary is limited to 30 characters (see function course_featured( $atts ) in /plugins/coursepress/includes/classes/class.shortcodes.php).

Is there a way to extend this to a longer length without modifying the plugin?

I have thought of something like this:

add_action( 'after_setup_theme', 'my_child_theme_setup' );
function my_child_theme_setup() {
	remove_shortcode( 'course_featured' );
	add_shortcode( 'course_featured', array( &$this, 'child_course_featured' ) );
function child_course_featured( $atts ) {...}

But I know this will not work because of the "&$this" reference. Solution is probably obvious for a php guru which i'm not.