How does Paragon work? It says "if you attack a ship you have already attacked this round, add 1 black die to your attack pool"

Is this regardless of range? Does Paragon have to attack the ship twice?

When an Upgrade Card refers to "You", it is referring to the Ship it is attached to.

Also, adding a Die is after you have calculated Range, so it can be of any colour regardless of Range.

Ergo, Paragon only works when you are firing at the same ship twice in one turn.

This Can only happen due to only 2 Scenarios:

1) You have the Ship Double-Arc'd

2) You are 2nd Player with Advanced Gunnery (and without Gunnery Teams).

However, it is an add die effect, so if you have a Concentrate Fire Dial, for example, you could Fire your First attack, and then, on your Second (due to the above, at the same target), you could add a Black Die, and then use Concentrate Fire to add a Second Black Die to your pool, as Paragon has put one in there, and Concentrate Fire lets you add a die of any colour that's already there

Yes you need to double arc the target or play the advanced gunnery mission.