Do you mean finding items to fill up your purple potion bottle?
If so, then there are no items that can do this. You need to play minigames in the commons of any world (in Wizard City, it's called the fairegrounds). Also, in Wizard City, there is a lady in the fairegrounds who sells one potion refill for 100 gold and three potion refills for 300 gold if you have three empty potion bottles.
Hope this helped, if this was what you were referring to.
