In Shir HaShirim (7,14) states חדשים גם ישנים, that the Gemara (Eiruvim 21a) learns “new ones” are easy Mitzvos, and “old ones” are difficult mitzovs. For an explanation see Maharsha.
To understand this verse in a simple manner, one should understand the nature of a person that upon receipt of a new item, one feels an affinity to that item. Bereshis 48, 16 “May they be called by my name and the name of my fathers, Avrohom and Yitzchak and may they increase in the land like fish.” Medrash Rabbah asks why like fish? And the medrash answers that fish live in the water, yet when it rains, they drink it with thirst. So it should be with the Jews, even though they grow up with Torah, when they hear a Chiddush in Torah, they should receive it with thirst.
This is an understanding of the known phrase “always the words of Torah should be as if new to a person.” This means that a person should always feel a positive affinity every time they hear the words of Torah and not like an old matter (even if already hear previously).
