In regards to the Civil War, how did the North start planning for after the war would be over?

Planning for after the war began as early as 1863.
President Lincoln had issued his Proclamation of Amnesty and Reconstruction. His plan
called for the Southern states to form a new government after ten percent of the
registered voters of 1860 took an oath of allegiance to the United States government,
thereby receiving a Presidential Pardon. Confederate senior officials and generals,
particularly those who left government service to join the Confederacy were excluded.
This was his famous "ten percent plan." Radical Republicans in Congress disputed
Lincoln's right as President to dictate terms of reconstruction and developed their own
plan, the Wade Davis Bill which provided that a majority of eligible voters must declare
allegiance; only those who took an ironclad oath of past loyalty could vote or serve in
State constitutional conventions; and slavery must be abolished. Lincoln pocket vetoed
the Bill, so it never became law. Lincoln had planned for a more compassionate
reconstruction, stating that the price of the lash had been paid in blood.
Unfortunately, he was assassinated before he could take further action.  Although not
ratified until late 1865, the Thirteenth Amendment which ended slavery was passed by
Congress before the end of the war.