How do you get into the animus after you beat brotherhood?

Step 1. Pause the gameStep 2. Select "Leave Animus"Step 3. Sit back and realize how pointless it was to ask this questionStep 4. Return to playing game

you just keep playing it.

Listen dont leave the animus i did and the game itched and i never could get back in and all thats out there is some people whom dont have much dialogue and a few hidden items.

first you choose a file and win

Through a system of trial and error, if you're skilled and determined, you could get through Assassin's Creed: Brotherhood without purchasing any armour upgrades.