not sure how you are curently making the whole "when tower is plante,d make all previous unlighted tiles in range lit and give 1 reputation for each newly lit tile.
maybe you can reverse it somehow to unlit the corresponding tiles and deduct reputation accordingly?
or other idea, IF you can count the tiles that are lit on the current map (which I know you definitely can since one achievements is literally lighting 450 tiles on a map) give the option to remove all towers at once, kind of like a reset button.
make all tiles, except the once that are usually lit by the start buildings, unlit.deduct reputaiton equal to the amount of tiles that were tower lit before the mass deletion.
oh and obviously make it like before areas were explored, so no trees, bushs, buildings in "dark areas" can be used until they are broguht into the ligth again.
soemthing like that.
so that once you have basiclaly explored the map, you can wipe out all towers (and other stuff if you want, mabe add a mass deletion button for that too while youa re at it. but give a "do you really wanna do that?" warning for both).
and jsut build stuff anew, into the perfect placement and positions, now that you know the full terrain and everything.
obviously would be a thing one only does if one really messed up the tower placement or simpy wants to optimises tuff for acheivement reasons , like having maximum of tree based barrel buildings or such.