High-level, behavioural language specification is seen as a significant strategy for overcoming the complexity of designing useful and interesting reconfigurable computing applications. However, appropriate frameworks for the design of behaviourally specified systems are still being sought. We are investigating behavioural language and compiler design based on the Circal process algebra, which is a natural framework within which to describe the concurrent activity of reconfigurable logic circuits. In this paper we describe an FPGA interpreter that exploits the inherent concurrency, hierarchy, and modularity of Circal and its circuit realization to automatically manage hardware virtualization. The techniques employed by the interpreter may be used to overcome resource limitations and adapt circuits to changing application needs at run time.