Hi Christy!
Great question! Generally, runDisney doesn't announce an entire year's worth of races at one time. They like to hear runners' feedback after events, and also see what else is being scheduled at Walt Disney World and Disneyland before deciding on a date.
So far, these dates have been officially announced for 2014:
January 8-12 Walt Disney World Marathon Weekend
January 16-19 Tinkerbell Half Marathon Weekend
February 20-23 Princess Half Marathon Weekend
The Expedition Everest still looks to be the first weekend in May, but it hasn't been updated on the website yet, so it probably isn't set in stone.
You can always find updated dates on the
runDisney website. They sometimes make announcements on the Run Disney Facebook page, as well, so you may want to "Like" it.
I would look for announcements of the other races in the first or second month following this year's events. They don't usually differ much from year to year.
Please let me know if you have any other questions.