How can I create a subroutine that saves my model run, allowing me to start the model from a stable configuration?

I'm currently creating an ecological model. It takes hours upon hours before it stabilises properly, making it difficult to work with when trying to analyse my results. How can I create a subroutine that would 'start' the model from a stable configuration (i.e. from when its already been run for hours).

I need to be able to do this so I can tweak some parameters, to understand how changing these factors would influence a 'stable' system. In essence, I would be influencing a stable ecosystem, rather than creating a new one from the changed parameters.