Creating a new assemblage vs Redesigning an existing assemblage

I need to discuss differences between designing a new system and redesigning an existing system in the context of ASD. My current studies focus on designing new systems and my results will inform mostly design of new systems/assemblages. However, I should also discuss what other dimensions a designer may need to consider for projects involving redesign. For instance, contextual design might provide with a useful basis to integrate agency sensitive qualities for redesign of existing systems.