I convinced DH to bump up his 401k contributions in stages, usually tied to lowered expenses. He had been contributing only 5% (to get the match). When they did away with the match, he wanted to stop contributing, but I had him switch his health insurance option to a cheaper one, and double the 401k to 10%. Very little change in net pay. When we paid off the mortgage, doubled 401k again to 20%. I began working part-time, doubled again to 40%. Lowering our AGI so much meant that our tax refunds increased (refundable credits), so we put that money towards Roths. Pay raises and more hours for me, increased 401k to hit the max.
I'm a math nut, I like to figure out our taxes and such, so I would work it all out beforehand and know exactly how much it would affect his net paycheck. Thus I knew whether we could swing it before I suggested it to DH. I also like to try to squeak out just a little more, so I'd stretch just a bit more each time. I knew that DH could always change his 401k deductions in a pinch, and we have a healthy EF to float us for a period.