The rules of the activity are determined by your coach, and will be sent to you via email when you are invited to participate in a new activity.
At this time, Brainshark does not limit the amount of times that you can attempt an activity because effective coaching is built on constant communication and feedback. The only exception to this for Machine Analysis enabled Coaching Activities.
You will be allowed to upload or record multiple versions of your submissions. Your coach (and you) will be able to see all of your submissions – there is no way to delete what you have previously submitted. This is helpful because together you can gauge your progress.
For more details on how to participate in a challenge, please view this helpful tutorial.