Does the soul get new instruction in its development, or does it merely uncover what it has always known?

If you say "experience" rather than "instruction", the question would be more accurate. Only God, or the Cosmic Self, can instruct the soul.

The soul is uncovering what it has always known. But at the same time, it is growing and enriching itself by taking into itself the divine essence of its earthly experiences. Meanwhile, the physical consciousness is becoming more and more conscious of the soul's unlimited divine capacity. In essence, the soul, being one with God, is uncovering what it has always known. But in the process of evolution, its becoming and knowing, knowing and becoming move together and are complementary processes in the lap of the Supreme Truth.