Devarim - Deuteronomy - Chapter 30
10: when you obey the Lord, your God, to observe His commandments and His statutes written in this Torah scroll, [and] when you return to the Lord, your God, with all your heart and with all your soul.
The Orthodox Phariseeic world speaks of, and has created a teshuva movement, where hitherto non-observant Jews become observant of Written and Oral Torah, halacha - in the form of the Shulchan Aruch and Talmud. This teshuva will, they believe hasten the process of Moshiach.
The text of the Torah, however, does not have these requirements. Instead, it asks us to observe what is Written in the Torah Scroll. The many rabbinic laws, which are not written in the Torah - and they do not claim that these are written, are therefore not a requirement to fulfill Teshuva.
The Torah is asking us only to keep what is Written in the Torah - this is the true teshuvah.