Arjuna's question is deeply practical. He is saying: yes, I want to meditate on You constantly. But in which form? In which things should I look for You? This is the question of every person who wants to connect with the divine but finds the abstract hard to hold on to.
The phrase keshu keshu is repeated — in which and which. This repetition reveals the depth of Arjuna's curiosity. He does not want just one or two examples. He wants the full picture. This is why Krishna will provide such a detailed catalogue in the shlokas ahead.