System of ordinary differential eqns-reset initial data

Hi, I have non linear system of 4 ordinary differential equations with time varying coefficients. I solved them numerically using ode 15s. It worked well. But now i want to stop my solver every 2 or 3 years and change the initial data and run it again. I dont know how to do it. Any guidance/help is greatly appreciated.

[Rose]

sorry walter! I apologize.