In most engineering disciplines, systems are designed by reusing existing components that have been used in other systems. It is certainly worthwhile to make use of existing architectures available as a whole or in part in the large space of designs instead of rebuilding the whole architecture. In collaboration with NASA Langley Research Center, we have been developing methods to reuse existing architectures for health and usage monitoring (HUMS) of aerospace structures. We discuss some of the key reuse techniques, which can be used to reuse existing available architectures in the design space. The primary contribution of This work is an iterative process model for employing reuse technique in a complex engineering system.