Most edX courses are offered several times over a year or two, but scheduling is up to the individual course team.
Some courses list future sessions as well as the current session. For more information, see How do I choose a course session?
For updates on new and repeat course runs, keep watching for our newsletter updates via email and periodically check our course catalog. You can also keep up-to-date by "liking" edX on Facebook, or following edX on Twitter.