Due to market requests many production systems undergo an everlasting evolution process that increasingly shifts traditional development activities for production systems to later phases of their lifecycle. As one of these activities, this contribution aims on the need for a semi-automated requirement verification mechanism during evolution. In this context the contribution proposes an answer to the question how a posteriori as well as a priori verification can be combined and which synergies arise accordingly. To do so, two appropriated approaches, one using an interdisciplinary modeling framework for model-driven engineering, and one using a PLC-signal based monitoring technique are presented that enhance each other by comparing estimated and actual system characteristics as verifiable requirement description. The resulting combined approach and its synergies are illustrated in two scenarios of an evolution case study.