Auto updating the schedule ship date calculated via ATP

Currently we are using the ATP functionality in order derive the schedule ship date on an order line. Consider a situation when there is no on hand, order line is scheduled via ATP functionality and the schedule ship date is 15 days from now.

However, we often have a situation when this information changes and the above calculated schedule ship date information is never updated.  For example, if product has an arrival date of 4/7/15 and is held up in customs and is going to arrive later than expected the date is not updated so as of now we are potentially misquoting the information to customers.  Or in the example above if the product is going to arrive sooner than 15 days, the schedule ship date is not updated or changed in the system automatically/dynamically.