On EnchantingPlus-1.7.2-2.0.1.6 if you try to enchant a book it takes the levels but does not apply the enchant to the book. On the other hand, if you obtain an enchanted book by other means and the config is set to allow you to disenchant items you did not enchant, then you can have infinite XP as the enchant is never taken from the book but the levels are refunded every time you click the button.
On EnchantingPlus-1.7.2-2.0.1.6 if you try to enchant a book it takes the levels but does not apply the enchant to the book. On the other hand, if you obtain an enchanted book by other means and the config is set to allow you to disenchant items you did not enchant, then you can have infinite XP as the enchant is never taken from the book but the levels are refunded every time you click the button.