User blog comment:The Professor Ozpin/A Little Help/@comment-25251916-20141003204056

Basically for the XE Prologue, you just need both Xenon and Estia in your party to be able to enter the dungeon. So that would mean you would just need to gain a Xenon, if you haven't already, from floors 1 to 100 and Estia from the rest 101 to 200.

If I would put up an estimated guess for their re-release, I'll place my bets on next month most likely. This also considers that they released it twice to help people to catch up. But eh who knows what Gumi has in planned for us, it's all speculation from tis point onwards. It'll eventually come back as the game progresses. Keep an eye out for any posts by Gumi on their forums or visit the special events tab from time to time.