WordPress Modify HTML functions - Drop this in your functions.php

funtions.php

<?php 
function start_modify_html() {
   ob_start();
}

function end_modify_html() {
   $html = ob_get_clean();
   $html = str_replace( 'Next Project', 'Next Offer', $html );
   $html = str_replace( 'Previous Project', 'Previous Offer', $html );
   echo $html;
}

add_action( 'wp_head', 'start_modify_html' );
add_action( 'wp_footer', 'end_modify_html' );