If you have logged into Rusty Hearts since the Reborn update, you'll notice that there are a multitude of new quests on your lv20+ characters, many of them having SP increase items.
Many of these quests have incorrect descriptions and do not complete when you do as the the quest tells you to. For example, the "Dirty Thoughts" quest tells you to clear Upper Plant VH, but it does not actually complete there.
There is an ongoing list of quests with their proper dungeon clear locations on the PWE forums here
Upper Plant | Atrium (Dirty Thoughts)
Lower Plant | Abandoned Wing (Dirtier Thoughts)
Cellar Sewers | Public Baths (Low Scores)
Wine Cellar 2F | Steamworks (Spiteful Sommelier)
Wine Cellar 1F | Collapsed Halls (Abyss-mal Assignement)
Cafeteria 1F | Guest Villa (Grade A Eggs)
Library 2F | Labyrinth (Study Up)
Library 1F | Conservatory (Deep Thinking)
Cafeteria 2F | Conservatory (Grade S Eggs)
Collapsed Halls | Atrium (Hall the Way Out)
I haven't done many of them myself since I'm working on Focus Changing the characters with the new weapons, but I can at least confirm that the first two are accurate myself.