An alternative reading is that G-d is not directing Noah, but reaffirming His commitment to existence.  Obviously Noah was worried about bringing new life. Why give birth, if in the future it might all be destroyed!?  So G‑d promised Noah that He would not. This explains the second communication. G-d was establishing a covenant and reassuring Noah. Understood!  But why repeat the mission statement to be fruitful. G-d had already made it abundantly clear that all was good to go Explanation: The flood was more than a punishment.

It was a global ritual bath that purged the world’s uncleanliness and generated a new existence. This was not going back to square one. It‘s more like a Mikvah. A non-Jew immerses, a Jew exits. Ditto the world. But what exactly was ‘new’ about the world? In the beginning, the world was locked within its own dynamic. It could not rise beyond its own limitations. To become ‘holy’ it had to rely upon input from Above. It could not generate holiness from within itself.

One might ask, why design the world in two stages?  Why create a world with a tenuous infrastructure, have it brought to a point where an apocalypse is necessary, and then begin again? Why not start out with the intended goal?Obviously, G‑d’s true desire is that the world itself should have the capacity to re-attain sanctity. A universe that will be holy only when flooded with His presence is not G-d’s ultimate interest. But can you expect creation to aspire to something it cannot even imagine? If you want a child to be an artist or a musician, take him to the museum where he can see great art or a concert hall to be uplifted by amazing melodies.  Similarly, if G-d desired a world to seek holiness, He needed it to experience overwhelming holiness. We can now answer the question: Why repeat ‘be fruitful’ after the flood? The statement to Adam was both a blessing and a directive. It expressed the overarching purpose of humanity: to increase not only our population, but G‑d’s presence. The blessing was that this world would feel G-d’s power. At the time of that blessing, it should have been fairly easy. After all, all of mankind lived in Paradise. But after the flood, the planet was anything but a Garden of Eden. It was bare, barren and ravished.  A new blessing and command were needed, one in accordance with the new circumstances. Though similar to the first, it truly was different. It was sustainable. More important, it wasn’t a blessing merely to increase G-d’s presence, but our impact.  It was a brave new world, one that not only relied upon G-d to shower gifts from Above, but on our new-found muscle to mop up the mess below.