Paying with Paypal Express programmatically for subscriptions orders

[pastullo]

I have a subscriptions system on my spree store where i programmatically create a new order, taking all the info from the previous one.
As long as the user create the payment in the normal checkout process, the PaypalExpress payment works great.

However, when i create the new order the next month and i run order.next to process the payment i get an error message that says:
Payment method identification was not specified

Is it possible to take a payment without the user manually doing the checkout process all over again?