Change Slug of a Plugin's Custom Post Type

gistfile1.php

<?php 
/**
 * Change Beer Directory plugin slug from 'beer' to 'soup'
 *
 * @link http://wordpress.stackexchange.com/questions/41988/redeclare-change-slug-of-a-plugins-custom-post-type
 */

function brewery_add_custom_rewrite_rule() {

    // First, try to load up the rewrite rules. We do this just in case
    // the default permalink structure is being used.
    if( ($current_rules = get_option('rewrite_rules')) ) {

        // Next, iterate through each custom rule adding a new rule
        // that replaces 'beer' with 'soup' and give it a higher
        // priority than the existing rule.
        foreach($current_rules as $key => $val) {
            if(strpos($key, 'beer') !== false) {
                add_rewrite_rule(str_ireplace('beer', 'soup', $key), $val, 'top');   
            } // end if
        } // end foreach

    } // end if/else

    // ...and we flush the rules
    flush_rewrite_rules();

} // end add_custom_rewrite_rule
add_action('init', 'brewery_add_custom_rewrite_rule');