What you're doing is setting a cookie "expires" parameter. Browser will clear the cookie up once it expires and you won't know about it — it simply will not arrive along with one of future requests.
Trick you can use to acutaly know if cookie is expired is to write a timestamp into a cookie and set its lifetime ("expires" value) to some faraway time (say, year 2037).
This way you can manually check if you still want to treat a given cookie as valid or if you want to renew it.
Sadly, you'd have to write your own code along the lines of
app.use(function(req, res, next) {
//Checking previously set cookie (if there is one)
var session = JSON.parse(req.cookies['session'] || '');
if (session && new Date(session.expires) < new Date()) {
console.log('User session has expired.')
}
//Resetting the cookie
res.cookie('session', JSON.stringify({ session: <sessionIDKeyHere>, expires: Date.now() + 3600000 }), {
expires: new Date(2037, 0, 1),
httpOnly: true,
secure: true //Do you have https? If no, set to false
});
next();
});