Set a time limit on Wordpress Cookie function.

I have the following function on our site,  which captures UTM tracking codes in cookies.  Users click on external ads, or through external sites to get to our site, and the UTM is stored in the cookie.

function set_ad_cookies() {
  $vars = array('utm_source', 'utm_campaign', 'utm_media');
  //$parsed = array();
  foreach ($vars as $k) {
      if (isset($_GET[$k]) && !isset($_COOKIE['orig_'.$k])) {
          setcookie('orig_'.$k, $_GET[$k], 0, '/', $domains['cookie_domain']);
      }
	  
      /*if (isset($_COOKIE['orig_'.$k])) {
          $parsed[$k] = $k.'='.urlencode($_COOKIE['orig_'.$k]);
      } elseif (isset($_GET[$k])) {
              // no need to handle get params here - they will be passed with $_SERVER['REQUEST_URI']
      #    $parsed[$k] = $k.'='.urlencode($_GET[$k]);
      }*/
  }
  
    if (!isset($_COOKIE['orig_utmsource'])) {
	  setcookie('orig_utmsource', $_GET['utm_source'], 0, '/', $domains['cookie_domain']);
	}
	if (!isset($_COOKIE['orig_utmmedium'])) {
	  setcookie('orig_utmmedium', $_GET['utm_medium'], 0, '/', $domains['cookie_domain']);
	}
	if (!isset($_COOKIE['orig_utmcampaign'])) {
	  setcookie('orig_utmcampaign', $_GET['utm_campaign'], 0, '/', $domains['cookie_domain']);
	}

}
add_action('init', 'set_ad_cookies');

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What I'm finding though, is the cookies are not expiring,  A user will come back to the site a few days, or weeks later, and still have the same UTM codes stored in a cookie.

Is it possible, and if so how,  can i modify this function, so that it kills the cookie after say 2 hours.  That way, if the user comes back to the site after 2 hours, through one of our ads, it has the new UTM codes stored in a new fresh cookie.