Probably, in consequence of the breach of Uzzah, the king thought it right that the Levites should never more be out of the path of duty, and therefore made a revisal of their office.
Related Commentaries of 1 Chronicles 16:4
1 Chronicles 16:4-6
4 And he appointed certain of the Levites to minister before the ark of the LORD, and to record, and to thank and praise the LORD God of Israel:
5 Asaph the chief, and next to him Zechariah, Jeiel, and Shemiramoth, and Jehiel, and Mattithiah, and Eliab, and Benaiah, and Obededom: and Jeiel with psalteriesa and with harps; but Asaph made a sound with cymbals;
6 Benaiah also and Jahaziel the priests with trumpets continually before the ark of the covenant of God.