You can abort CST part way through, and it asks if you want to save the results. I don't know if you can use those to start again part-way through.
I think you might need to start from the beginning again, but at least you have some results. From the excitation signal results and the energy results you can see how much energy is still left bouncing about in the system. This corresponds to the ripple that remains on the S-parameters.
Malcolm White Thanks very much for your reply but It usually saves the results incase of sudden termination due to power cuts but in the recent license version it is not happening. I am not sure if there is any settings for that but I am would like to have that options otherwise my long duration simulations are getting affected.