Embedded systems design process focuses on three areas: modeling, validation and implementation. Typically such procedure assumes constant number of tasks in every instance of designing procedure. Thus the designer must predict all possible tasks executed by the system. Serious problems appear when the system has to execute unexpected tasks. In this case the design process must be repeated. We propose a new approach in embedded system design process which covers such situation. In the approach unexpected tasks are assigned to previously allocated resources. Therefore the system can execute more tasks that were predicted by the designer.