Hi - no need to reconfirm - all you need is the Confirmation Number which they e mail to you at the time of booking.
In fact I had to get back from Madrid urgently in January and I telephoned a friend in the UK who booked me on Ryanair and then texted me the confirmation number - I simply quoted it and they issued a boarding pass.
I agree, no need to confirm your flight. But just in case you stress about this, it is possible to check in 5 days before your flight on their website. This is what they say:
You can save time at the airport, by using our Online Check-In Service - Check’N Go to print your own boarding card. Online Check-In is available from 5 days up to 4 hours before the scheduled flight departure time.
Although it's not necessary to reconfirm, you might want to check your booking on their website a day or two beforehand. If you're planning on checking in luggage they won't allow you to check in online, however you can still view your reservation details. Alternatively, check your email a day or two earlier as they always send a pre-flight reminder to the email address given at the time of booking. This should alert you to any last minute schedule changes. If you arrive at the airport for the originally scheduled time, and your flight left hours earlier, Ryanair are merciless.
As you guys said- no need to reconfirm, but I would strongly recommend to login to their website and check your flight 24 hours before departure. I'm using ryanair 6-8 times a year since 2004 and it happened to me 2 or three times, that my flight departure have changed (for one day earlier than planned in one of these cases) without ANY NOTICE from ryanair (not even an automated e-mail).
It is very easy to check your flight departure- just need to have your confirmation number and credit/debit card number (the one used to pay for the ticket)...