(Kadamba Kanana Swami, 29 September 2013, Melbourne, Australia, Srimad Bhagavatam 2.2.36)
Why are topics of Lord Krsna always fresh?
Well, it is said that when Krsna and Balarama left Vrindavan, they were taken to Mathura. Then after they killed Kamsa and so on, then their father felt, “Now after all this time, I was not able to do my duty as a father because as a father, my duty is to offer my sons some education.’”
So then, he made arrangements for some education and sent Krsna and Balarama to Sandipani Muni where they got educated very nicely. They served their guru very nicely and then in the end, Sandipani Muni gave benedictions to Krsna and he said, “Your words, whenever they are spoken about you, it will always remain ever fresh.”
So therefore, the pastimes of Krsna are always ever fresh and the words of Krsna are always fresh because of the benedictions of Sandipani Muni.
Of course, it is said that Sandipani Muni is like a mountain and the mountain gets water from the clouds and then it gives that water in the form of rivers, and distributes it to everyone. So ultimately, whatever Sandipani Muni got, he got from Krsna. So, the real answer to your question is that it is because Krsna is ever fresh. Therefore, his words and descriptions about him are also ever fresh!