Rabbi Yosef Yitzchak of Lubavitch once said: “The blessing shehecheyanu on Simchat Torah is not only on the holiday, but also on the Torah.” This raises a question: The blessing shehecheyanu is generally recited over something new-why do we make the blessing for the joy of completing the Torah?

The explanation is that after reading and learning the whole Torah during the past year, and its completion on Simchat Torah-a “new radiance” is added to it; it is renewed. As we begin to learn anew (according to Jewish custom of beginning again immediately), it is, so to speak, a new Torah, a higher Torah; and for this we say Shehecheyanu.

Each Jew expresses this novelty according to his role-a full-time Torah scholar, in learning and understanding the Torah in a new manner; a businessman, with new vitality in learning the Torah and keeping it.

(Likkutei Sichot, vol. 19, p. 371)