vs. 31 And to offer all burnt sacrifices unto YHVH in the Sabbaths, in the New Moons, and on the set feasts, by number, according to the order commanded unto them, continually before YHVH.

Here is a reminder to always observe Sabbaths, New Moons and the Feasts of YHVH.

The next reference in a similar vein is in II Chronicles 2:4.

vs. 4 Behold, I build an house to the name of YHVH my Elohim, to dedicate it to Him, to burn before Him sweet incense, and for the continual shewbread, and for the burnt offerings, morning and evening, on the Sabbaths, and on the New Moons, and on the solemn Feasts of YHVH our Elohim. This is an ordinance forever to Israel.

Solomon proclaimed this reminder to observe Sabbath, New Moons and the Feasts of YHVH. In this case there is an additional notation not found previously: "This is an ordinance forever ..."

Another reference to Solomon observing New Moons is found in II Chronicles 8:13.

vs. 13 Even after a certain rate every day, offering according to the commandment of Moses, on the Sabbaths, and on the New Moons, and on the solemn Feasts, three time in the year, even in the Feast of Unleavened Bread, and in the Feast of Tabernacles.

The next citation of New Moons is in II Chronicles 31:3.

vs. 3 He appointed also the kings portion of his substance for the burnt offerings, for the morning and evening burnt offerings, and the burnt offerings for the Sabbaths, and for the New Moons, and for the set Feasts, as written in the law of YHVH.

This verse records the declaration of Hezekiah to observe Sabbaths, New Moons and the Feasts of YHVH. This was a period of rediscovery and restoration of the divine commands of YHVH by King Hezekiah after more than 200 years of evil kings and wickedness in Israel since the time of King Solomon.