Changing the 'next' and 'previous' page text

Hello, i am trying to change the ‘next’ and ‘previous’ text at the bottom of the list of blog posts to say ‘newer’ and ‘older’. I have found the function in content-extensions.php, named function attitude_next_previous(). The problem I am having is that the function is not pluggable so I can’t just copy it into my functions.php and change what I need to change. I have tried removing the function and making a new one but I can’t get it to work. Does anybody know the correct way to do this? For reference, here is the function:

add_action( 'attitude_after_loop_content', 'attitude_next_previous', 5 );
/**
 * Shows the next or previous posts
 */
function attitude_next_previous() {
	if( is_archive() || is_home() || is_search() ) {
		/**
		 * Checking WP-PageNaviplugin exist
		 */
		if ( function_exists('wp_pagenavi' ) ) :
			wp_pagenavi();

		else:
			global $wp_query;
			if ( $wp_query->max_num_pages > 1 ) :
			?>
			<ul class="default-wp-page clearfix">
				<li class="previous"><?php next_posts_link( __( '&laquo; Previous', 'attitude' ) ); ?></li>
				<li class="next"><?php previous_posts_link( __( 'Next &raquo;', 'attitude' ) ); ?></li>
			</ul>
			<?php
			endif;
		endif;
	}
}

Thanks