'Add' in the Bible

Ah! Ariel, Ariel, [the] city [where] David encamped! Add year to year, let festivals recur.

"Oh rebellious children!" {declares} Yahweh, "to make a plan, but not from me, and pour out a libation, but not [from] my Spirit, {so as to add} sin to sin.

"Go and say to Hezekiah, 'Thus says Yahweh, the God of David your ancestor: "I have heard your prayer; I have seen your tears. {Look, I am going to} add fifteen years to your days.