Admitting the old plan failed is the first line of the new plan.

You cannot plan from a position you have not admitted you are in. As long as the old plan is officially still running, every new idea has to pretend to be a small adjustment to it. Saying it failed is not a confession. It is the first usable sentence.

Write it plainly somewhere, in one line, with no excuses attached. Then write what you actually know now that you did not know when you made the old plan. That second line is usually where the new plan starts.