Say what? Exit plan for a non profit? Google "define: exit plan" and you'll find nothing but talk about how the owners of a normal for-profit business generate cash from the business as they sell it. The "exit" refers to turning ownership in a business, usually as shares, into money.
Obviously if that's what the exit means then you can't talk about an exit plan for a non profit because it doesn't have owners in the normal sense and isn't supposed to be sold.
I assume what you mean is how you plan to dissolve or liquidate a non-profit organization, and that's a matter for attorneys first. Non profits have a lot of legal rules governing what happens to them, and what happens to the value, branding, effort, and money that people have put into them.
If you're trying to change the situation/charter/foundation/ownership of a non-profit organization, then to write a plan for that do a simple plan that includes objectives, assumptions, strategy, important steps, relevant financial projections, responsibilities, and follow-up.