User blog comment:IamJakuhoRaikoben/Chapter 384: Attack of the Stars, Review./@comment-3424593-20140516074407/@comment-7418318-20140516093535

I just had another idea. Maybe the ritual to restore the key can only be performed within the Celestial Spirit Realm and takes several days.

With Lucy suffering greatly from the seven year timeskip and also suffering a bit from the three month one, it's not something Lucy would do lightly.