Ryanair also is tweaking their summer 2013 schedule now. Before all routes and frequencies were identical to summer 2012 but now it is being corrected so any earlier announcements for new routes and frequency increases are starting to appear. This post below that I made a couple of months ago will be of some use now. Have already found for instance that London Stansted to Patras/Araxos isn't planning to be resumed for 2013 but looks like Kos and Rhodes will do. If you can make sense of it, have a look around.
Very strangely Ryanair's booking system seems to have some sort of glitch which I've found to indicate what routes may or may not operate in the next schedule season before anything goes on sale. If you select a flight route inthe next and currently unavailable schedule season (in this case "summer 2013") it will obviously show no available flights. Despite knowing this, try it anyway and make sure you select the return date to be exactly 1 week after the departure date but with flexible travel dates (just to make what I'm about to say easier to see).
If the selected departure date (highlighted in yellow) is not centralised so is basically not showing 3 alternative dates to either side but instead 6 alternative dates after and isn't actually the specific date you selected but instead 3 days before coming back, but the return flight is centralised (with 3 alternative dates toeither side of the selected date) then this simply means there is no flights available. Don't ask me why its like that, I have no idea, but it is.
If however BOTH the departure and return flights ARE centralised (with both showing 3 alternative dates either side of the selected date) and the departure date IS now the exact date you selected then this seems to indicate that Ryanair are planning to operate this route at least once at some point within that time.
For some routes, it can change and isn't 100% accurate but is correct the vast majority of the time and becomes more accurate the closer you get to flights being released for booking, however as we know it can still change after this point, especially with Ryanair as they are well known for cancelling routes or starting new ones at short notice! Of course you can't see what new routes are being planned since you cannot yet select them in the booking system.
People will probably think I'm just talking complete rubbish however I noticed it several years ago and have become certain that it is to do with what Ryanair are planning to operate and what not to, and I'd say that "planning" is the operative word there!