Change WPUF Save Draft Button text

/** Change WPUF Save Draft Button text **/
function change_wpuf_draft_button_text ( $string ) {
    if ($string == "Save Draft") { // String you want to change
        $string = "Draft & Save Post"; // Insert your string
    }
    return $string;
}
add_filter( 'gettext', 'change_wpuf_draft_button_text' );