What does "Ya'an u've'Ya'an" mean? Why the double expression?
Rashi: It means 'because' (as a punishment for), 1 which the Torah repeats (presumably for emphasis).
Rashi (in the initial edition) and Rashbam): What the Torah is saying is that it is because Yisrael despised Hashem's judgments and because they loathed His statutes that the land became bereft of them.
Targum Onkelos and Targum Yonasan: 'Curses instead of blessings 2 will come upon you'.
Why does the Torah return to curse Yisrael after having written "Vezacharti es B'risi Ya'akov ... "?
Ramban: This refers to the period after Koresh initially granted Yisrael permission to return to Eretz Yisrael and ordered the rebuilding of the Beis-Hamikdash, when the order was withdrawn, and the land continued to bereft of Yisrael and the land continued to be appeased for the broken Shemitos for another nineteen years, until the second Beis-Hamikdash was built and they sanctified Yerushalayim with two Todos. 1 That was when the Kedushah returned to the land and they once again kept the Shemitah. 2