I just want to be clear on this bit, after re-rolling a die, it can still be changed into a different result, yes? I'm thinking of Redline with his target locks, in combination with Guidance Chips. If the TL re-roll doesn't come up with a hit, the chips can then change it. I suppose it would also apply to the Palpatine change.

I've heard people say that the chips wouldn't work well with Cluster missiles, but I think with Redline you are pretty much guaranteed three hits on both rolls.

Changing a die result is not the same thing as rerolling it. Therefore, yes, you can modify a die result that has already been rerolled. For example, you can spend a target lock, reroll a blank, get an eyeball, and then spend focus to turn that eyeball into a hit. Guidance Chips works similarly.

The reason Guidance Chips is not as good as it could be with Cluster Missiles is the "once per round" limitation it has. You can use it on either the first or the second attack of the Cluster Missiles, but not both.

After rerolling you can still change the results using tokens and card abilities.

There are upgrades that specify wether or not you can change a die after it has been rerolled.

Sensor Jammer, for instance, changes a hit result to a focus result. It also prohibits the attacker from rerolling it. He can still use a focus token to turn it back into a hit result though.