What if there was an increasing vote threshold to get reelected after each incremental term served?
Whereas the initial election simply requires getting more votes than any other candidate, maybe the first reelection (second term) requires a majority (>50%), and the second reelection (third term) requires >52%. Regardless of the actual numbers, the goal is to tie reward (reelection) to performance (constituent satisfaction).
This could be viewed as an alternative to term limits. It sets an appropriate expectation that more experienced legislators should be more productive/effective than the newer ones.
Ideally this mechanism would effectively weed out the poor performers while enabling the effective legislators to continue leveraging their accumulated experience for the benefit of all Americans.