Conversational Agents (CAs) provide the means to foster user experience design through seizing their interaction capability, knowledgeability, and human-like behavior. To support practice and academia in designing CAs, IS researchers have been creating design knowledge in the form of design principles (DPs) guided by the Design Science paradigm. However, scientific literature in this vein is dispersed and lacks an axis of cohesion and transferability to sustained practice usage. This raises the question of reusability of design principles in the realm of CAs. Therefore, in this study, we conduct a Systematic Literature Review to retrieve and assess design principles of existing design science papers dealing with CAs with regard to their reusability. Our findings indicate that the Design Science community, in our case in the domain of CAs, seems to face challenges in creating reusable design principles. We discuss this observation and provide avenues on how to move forward