The architectural design of software systems is not a trivial task, requiring sometimes large experience and knowledge accumulated for years. Reference architectures have been increasingly adopted as a means to support such task, also contributing to the standardization and evolution of these systems. Although considerable time and effort are devoted to design these architectures, an outdated description is still found in several of them and, as a consequence, resulting in their non-continuation. This article presents guidelines to evolve the description of reference architectures, considering different types of stakeholders and required tasks. To complement our statement that the guidelines are correct by construction as they were grounded in widely known international standard ISO/IEC/IEEE 42010 and literature, we also briefly present a qualitative analysis comparing the guidelines with an ad hoc way (commonly occurred in reference architectures). We believe solutions like these guidelines are necessary and could further contribute to the sustainability and longevity of reference architectures.