Jonathan Edwards believed that Christians in heaven will only increase in holiness and happiness forever and ever.
He based this on the idea that, once in heaven, a Christian's bank of memories will forever be growing, which only means that the number of ideas in their mind will forever be growing also. Of course, this is just another way of saying that a Christian's knowledge will always be increasing—and here is Edwards' connection—
. . . and if their knowledge, doubtless their holiness. For as they increase in the knowledge of God and of the works of God, the more they will see of his excellency; and the more they see of his excellency . . . the more will they love him; and the more they love God, the more delight and happiness . . . will they have in him. (Miscellanies #105)
(Edwards argues elsewhere that the essence of holiness is love for God, which explains why, in this quote, he refers to love increasing but doesn't mention holiness after the first sentence. They are the same.)