Smart Transformers (ST) are a potential solution for installing intelligent nodes in the electrical distribution grid, which can provide DC connectivity and are capable of providing grid services the traditional low-frequency transformers was not able to provide. However, the reliability of STs is one of the main challenges, limiting its application. To improve the reliability of STs, it is proposed to control the power in a modular ST architecture in order to control the remaining lifetime of its building blocks. Therefore, unequal power sharing through the cells based on the remaining useful lifetime, known as power routing, has been proposed for different converter topologies. However, existing literature has not investigated the impact of power routing on the ST on a system level. This paper focuses on the design and implementation of lifetime-based power routing control based on virtual resistances tailored for an ST consisting of Cascaded H-bridge (CHB) and Dual-Active Bridge (DAB) converters.