This would fix so many problems. The copyright and patent laws would look dramatically different if they were written today. You wouldn't have silly state laws like it being illegal to have a goatee in Massachusetts, or it being illegal for moose to have sex on state highways in Alaska (how do they enforce that one?) We might rethink the war on drugs now that we've been at war for a generation. The 2nd amendment probably either shouldn't exist or should protect the rights of people to own much more than guns, now that a guy with a gun is easy fodder for a tank. You really need to legalize Stingers and TOWs to fulfill the original purpose of the 2nd amendment.
Curiously, the sunset provision on all laws should itself be subject to sunset provisions. It makes sense to make laws persistent when the world does not change very much over decades. In fact, we probably would not have developed our post-industrial society without it. It's only when the world starts getting massively remade on the timescale of 5-10 years that it makes sense for laws to expire and be remade themselves.
If only this didn't cause logical paradoxes at the time the sunset provision itself sunsets...