After the unmitigated success of my previous question on Elan

, I have another question.
With most (if not all) of the Beryls and Shajads, the total Elan requirements of the Gifts you can receive adds up to more than 100, so even if you have the maximum possible, you have to choose which Gifts to take.
But what happens if your Elan increases, and you could potentially gain access to a new Gift but because of Gifts you bought when your Elan was lower, you don't have enough available?
Can you remove Gifts that you've been granted, or are you stuck with them?
e.g. A Priest starts off with Elan 60, and has Gifts worth 55 points of Elan. As time goes on, he gets to Elan 70 through his actions, and there's a Gift with a requirement of Elan 70, but a cost of 20 points.
Can he remove an earlier Gift worth 5 points to take advantage of this? Or does he have to wait until he hopefully gets to Elan 75 to take it, at the risk of never being able to afford the Elan 80, Elan 90 and Elan 100 Gifts?
It's just something I've never exactly been clear on.