For those that might be unaware, NASA-SE usually has a discounted sigh-up period that runs from the RA event until 31Dec. It’s a pretty big discount so you can save a lot of money if you’re willing to sign up for 2015 events well in advance.
The way to do it most efficiently is to sign up for all the events except for the last 2. This way if you have to cancel out of an event next year, you can just move your registration to one of those last 2015 events. You can’t move a registration to 2016.