In the last years, complex applications from various domains are implemented in embedded devices. These applications make extended use of the dynamic memory to store dynamically allocated data structures. The implementation of these data structures affects the performance and the memory usage of the embedded system. A methodology for selecting the appropriate data structures at design time is the Dynamic Data Type Refinement (DDTR) methodology. In this paper we present an extension to this approach, by presenting a methodology for adapting the dynamic data structure implementations to the requirements of the embedded system at runtime. By implementing the proposed methodology to a set of various applications from different domains, we achieve a dynamic memory size reduction up to 32\%.