One of my previous managers said “Operating plans become outdated as soon as we finalize it”. She was kidding but there is some truth to it. One cannot think of annual plans as static but as ‘ever-growing’ to address the changing market conditions, strategies and risks. The operating plan should be refreshed quarterly.
The steps need not be as comprehensive as preparing the annual plan but it nevertheless needs to reflect the changed circumstances.
During your monthly/quarterly “budget versus actuals” meeting with the department heads, discuss how their department’s objectives and hence spending has changed. Incorporate those changes into the revised plan.
Dont just throw away your old plan because it is a good tool to refine your next year’s plan.