I'd like to rest my armies so that they don't lose too much cohesion.

[Mahatma]

Let's say army cohesion is 100%, and each day of movement reduces it by 2%. I want to move two provinces distance, and the only way I can do this is by having the army march for 20 days so that cohesion becomes 60% before recovering. How do I move them so that they can march for 5 days to 90% cohesion, then rest for a few days, before marching again? Or any other similar method that allows cohesion to recover.

[arsan]

You can't except by moving just one region each turn.
To reduce cohesion loss try to move on defensive or better still on pasive posture if there is no enemy around.
If you move into regions with 100% enemy military control your army will change to offensive posture even if you order them to move on defensive. To avoid this problem you can send some cavalry in ofensive in advance of the army to get some military control before the main army arrives to the region so it can keep on going on defensive posture.
Cavalry in offensive with green rule of engagement and avoid combat orders are pretty good at taking military control of enemy regions while avoiding unwanted combat with the enemy.

Regards!

[Ebbingford]

Don't forget to check what the weather and terrain is like through the regions that you want to move through. If it is forrest without a road then if you move when it is raining it will take longer and you will lose stacks of cohesion. Mud is a killer as well. Sometimes it is quicker to rest for a turn and then move later than to try and move if the weather and conditions are against it.