The really simple answer is running more trains with more cars.
In June of 2021, Amtrak lost ~$836,200,000 providing ~1,665,300,000 passenger miles, or a loss of ~$0.502 per passenger mile.
In June of 2022, Amtrak lost ~$724,500,000 providing ~3,381,000,000 passenger miles, or a loss of ~$0.214...