How do you handle flashing when putting on a second layer?

I've put on roofs before, but I've never put on a second layer of shingles. Now that I am, what do I do about flashing? Do I put on a second flashing layer? Do I replace the old flashing? Do I just leave the flashing as it is?





Any help greatly appreciated!How do you handle flashing when putting on a second layer?
To the best of my knowledge you just lay the new shingles on and go for it. If the flashing is Steel you would need to put on another flashing over the old and shingle as usual.