How can I use fitnet coefficients of my older neural network in training a new one?

Hi everyone,

I am using neural network for function fitting using fitnet command. First, I trained it using some inputs my input is a matrix 231x5000 and target is 8x5000. Now I want to add new inputs to my input matrix and to train a new neural network. The new input would be (231 + y)x5000 and the target is the same as on old problem 8x5000. How can I use the coefficients that I obtained from the first model in order to increase the computation time?