This paper examines the role of Software Aging and Rejuvenation and their effect on Critical Information Infrastructure and thus Critical Infrastructure maintainability. Software systems tend to degrade over time by entering a failure-prone state and showing decreased performance. It is suggested that Critical Infrastructures are especially susceptible to the detrimental effects of Software Aging and that common Software Rejuvenation remedies are not suitable in this context. Instead of treating re-emerging symptoms, an alternative approach is presented that seeks to monitor, analyze and, identify potential root causes like underlying architectural problems of software used in Critical Infrastructure. Results of first applications are shown and intended next research and development steps discussed.