Generated training plans can be rebuilt within the first 2 weeks of the training plan. When rebuilding the plan, the start date will remain the same and only the future dates will be rebuilt (i.e. if you are 1 week in to a 6 week plan, only the last 5 weeks will be rebuilt). This allows some flexibility if you need to make a change on the amount of time available or have a change of plans on an event you are planning to ride.