I built a whole city in hard world and there are creepers exploding it all the time. It is only small but there are enough builds for it to be really hard to rebuild it in a different world. I was wondering if there was a way for admins to copy the island a built all the builds on, and paste it into peaceful. I really hope there is a way to do the because me and my friend gave it a nickname of "Creeper explosion ville" instead of "Froggerville", because there are so many holes everywhere and our builds get exploded all the time.

Unfortunately, there is not a way for admins to copy/paste player builds.

As I recommended earlier, you can light up your area or have a few cats to keep them away. If you break a block in the ground, use a light block (like glowstone or shroomlight etc.) and then place moss carpet over the top, it's like "hidden lighting".