Once an individual moves on from one job to another, they do not continue to receive their salary from the previous job, and it should be the same for ALL members of Congress.
If a Congressmen is not re-elected, or if they choose not to run for re-election, they have lost/are giving up their position, and thus should not continue to be entitled to that position's salary. This would save the government millions, if not billions, over time and, quite frankly, would make more sense than the current practice.