Rudey,
Yes they need to pay initiation fees, and yes they need to pretty much pledge all over again. Then they also need to prove for a period of time that they can sustain the momentum.
Why would they fail? The chapter is not unified in wanting to go national...reluctance to give up old traditions and adopt new ones...lack of alum support for the change...sticker shock over the usually increased dues...can't maintain momentum after the "movers and shakers" who pushed for national affiliation graduate...I could go on, but I think you get the idea.
And now that I've depressed myself I'm going to go stick my head in the oven!