'Add' in the Bible

Woe to Ariel! Ariel, the city where David encamped! Add year to year; let the feasts come around;

"Woe to the rebellious children," says Yahweh, "who take counsel, but not from me; and who make an alliance, but not with my Spirit, that they may add sin to sin,

"Go, and tell Hezekiah, 'Thus says Yahweh, the God of David your father, "I have heard your prayer. I have seen your tears. Behold, I will add fifteen years to your life.