Keep $_SESSION alive with autorenewing counter

Keep $_SESSION alive with autorenewing counter

I'd like to keep sessions alive for three days, and whenever they visit
the page it is renewed up to three days again. Basically if they don't
visit the site for three days, their session drops.
ini_set('session.cookie_lifetime',60*60*24*3); //saw on a similar SO question
session_start();
The above piece of code is at the top of top.php, a file that is
include()ed on every single page.
$_SESSION["username"] = $username;
$_SESSION["password"] = $hashedpass;
$_SESSION["authtoken"] = $authkey; //authentication key
The above is on login.php which sets the $_SESSION data according to
verification it exists in SQL.
Maybe this is a function of WAMP, but whenever I close the browser, the
session terminates despite the php.ini params being changed. Am I perhaps
using the wrong bit on line 1 of top.php?