Yes! You may re-take a future session of an edX course. Each offering of a course is assessed independently and most edX courses do repeat. It is not possible to start fresh in a course session you have already begun \.
If you had paid for the verified certificate track in your previous session and you wish to try again for the certificate, you will need to pay a new verified enrollment fee. The fee only applies to the session it was paid in, and helps edX and the course team with the course production and hosting costs.