The Rebbe's annual Sicha to the attendees of the Annual International N'shei U'Bnos Chabad Convention
Although the Festivals repeat themselves year after year, Jews are commanded to see Torah and Mitzvos as given anew each and every day. Especially when it comes to women, we always mention how young they are -- not just to be polite, but because when a woman is connected to Torah and Judaism, then not only does she not grow "old," she becomes renewed, refreshed and younger through her connection to the Source of blessing. This makes her accepting the Torah this year more profound, more alive, and more joyous.
This also sheds light on the fact that in this day and age, women and girls -- even very little girls -- study parts of the Torah which in the past they'd rely on their husbands or brothers to know. It used to be enough for women and girls, when they had Torah questions, to ask their brothers or husbands. But we have merited that as more of the Torah has become revealed, the Jewish custom has also become for women to study much more Torah as well -- to the point that it even happens that a husband or a brother will turn to his wife or sister when he has a question in Torah learning.