Extend the life of the Public Post Preview plugin to 10 days.

snippet.php

<?php
// Download this snippet as a plugin and more at: https://wordbits.io/snippet/extend-the-public-post-preview-plugin/
// Created by: Lauren Pittenger
?>

<?php
/**
* Public post preview pugin: extend expiration to 10 days
*/
add_filter( 'ppp_nonce_life', 'fans4thecure_nonce_life' );
function fans4thecure_nonce_life() {
    return 60 * 60 * 24 * 10; // 10 days
}