Use the Clear Gem and check the tablet above you. To start NG+ with your chosen bonuses, activate them as required and then go through the doorway at the top right.
It doesn't "activate the defeat score" because there's no winning or losing, per se. It calculates the scores for both formulae, and takes the higher or the two. So the only way to have it count the victory score is to have a victory score calculation higher than the defeat one. If you haven't done that, there's no higher theoretical victory score to calculate.