Nofollow specific links in NavBar?

I’m trying to nofollow specific links in my navbar.

The code in my header.php looks like this:

<div id="navmenu-wrapper">
                    <ul>
                        <?php themefunction_page_menu(); ?>
                    </ul>
</div>

The code for themefunction_page_menu in my theme fuctions.php looks like this:

function themefunction_alter_page_menu($string) {
	$string = themefunction_alter_list_pages($string);
	$pattern = array('/<div[^<>]*>/','/<\/div[^<>]*>/');
	$replace = array('','');
	$string = preg_replace($pattern,$replace,$string);
	return $string;
}

Full theme functions file

In the past I used the following code to solve this problem, but the code was different and I’m not sure how I can implement it into my theme. Any suggestions would be greatly appreciated!

Old code:

// Add post ID to nofollow separated by comma
$nofollow_posts = array(1, 2);

if ( in_array( $page->ID, $nofollow_posts ) )
	$nofollow = ' rel="nofollow"';
else
	$nofollow = '';

$output .= $indent . '<li class="' . $css_class . '"><a '. $nofollow . 'href="' . get_page_link($page->ID) . '" title="' . attribute_escape(apply_filters('the_title', $page->post_title)) . '"><span>' . apply_filters('the_title', $page->post_title) . '</span></a></li>';

I would then change the array(1, 2); to the post i’ds I wanted to nofollow.