Diplomacy is the option we have to take and I think we have leverage. The UN sanctions were backed by China in the Security Council. China is North Korea's closest ally and China wants NK to continue to exist as a buffer to South Korea but would prefer they don't have nuclear weapons and that Kim wasn't causing so much turmoil. The sanctions will hurt NK and hurt more if China participates like they should after the UN vote. I think 3 way talks with NK, China and the US could result in a resolution. The resolution could be that NK gives up the nukes in return for lifting sanctions and economic help or something like that. The bad option would be a military attack to try to destroy their nuclear weapons and program because I think Kim is crazy enough to open fire on SK in retaliation. That would probably mean a real war with the same problem we had before and that is that China doesn't want a unified Korea friendly to the west more than them on their border. Resolving the war would be a harder nut to crack.
I doubt North Korea gives up their nukes. I think we are stuck with trying to freeze their program. What their leadership learned from Iraq is simple, if one doesn't have nukes one can be invaded by the US. If Saddam had nukes, he'd still be in power (or dead from some other means). I don't know that Kim is going to trust that we aren't going to invade if he gets rid of them.*
* yes, with their artillery near Seoul, the horrible terrain, and terrible winters an invasion is ludicrous. But even if highly unlikely that is far different than impossible if they keep their nukes.