ctrl + shift + n

new layer
apply image
make changes to ur new layer
click on lighting layer -- or w/e layer u want
ctrl + j

copies the layer
move that layer in front of applied image.
thats the best advice i can give... then you can erase the top layer, or change the fill, or w/e u want so that u can still see the applied image changes, but can also move the stuff on the bottom around.
... of course this only works to a certain degree... you can't completely move an object anymore.