Stripe - PHP - Upgrade Subscription Plan, Invoice Now

gistfile1.php

// Retrieve the customer:
$customer = Stripe_Customer::retrieve($customer_id);
 
// Retrieve the subscription being updated:
$subscription = $customer->subscriptions->retrieve($subscription_id);
 
// Change the plan:
$subscription->plan = '25_monthly'; // Was 10_monthly
 
// Use proration (default; not required):
$subscription->prorate = true;
 
// Save the changes:
$subscription->save();

// Invoice now:
Stripe_Invoice::create(array(
	'customer' => $customer_id
));