Is there any "purpose" to beating the manor after the first time?

[Cashews]

Apart from say, the bonus rainbow gems you get for beating the boss. Are there additional unlocks for beating Roelynn more than once, or per character?

[Awmax]

There are no more unlocks after you beat the new area once as any character, although you can still go for fun or to take advantage of an extra floors' worth of shop and restaurant buffs before you advance to kaminela and ericha.