It is a pretty standard game rule that you cannot re-roll a dice that you have already re-rolled. But I have been looking for that in these rules and I can not find it. I am looking for the exact wording becasue I am curious defensive re-rolls (from R7) interact with offensive re-rolls from something like TL or Howelrunner.
I see a couple of possibilities-
1- there is no rule about re-rolling re-rolls
2- Dice that have been re-rolled cannot be re-rolled again. So a ships with an R7 droid forces tah attacker to re-roll his/her hits, those dice cannot be re-rolled by the attacker
3- Dice that have been re-rolled cannot be re-rolled by the same player. So if the defender forces an attacker to re-roll attack dice, the attacker can still do his/her re-rolls.
Again I am interested in the exact wording from FFG