Is it possible to extract FB alks out of enhanced leaf/changa into ISO to make a new batch?

Yes.

I wonder though if depending on the plant used for enhanced leaf, too much natural plant acids will turn freebase into some salt form which will not dissolve well in IPA. I doubt it but anyways just a possibility I thought about.

Even if it did, though, it would be easy enough to just make a paste of enhanced leaf with a bit of extra sodium carbonate, let it dry and then pull with IPA

So how could one go about this? Soak the leaf in iso overnight? Soak the leaf in iso in a warm water bath and stir occasionally?

Id just soak it for a couple of hours, filter and then evap the IPA (or evap onto the other leaves you want to use). Id do a second round of soaking on the herbs to make sure you got all of the DMT, and Id keep the spent leaves just in case, if for some reason you feel that the new leaves are weak or whatever, Id add some sodium carb to them and do yet another IPA soak.

Do you know how much DMT is there? Also if I may ask, why do you want to do this, whats wrong with your enhanced leaves as they are?

I've been trying to make Changa. I tried one with just plain leaf and that one doesn't have any harmala push to it and I made another batch with 5-10x caapi infused on mint but I made it really harmala heavy lol. I'm trying to take all the spice from the plain leaf and put it on the 5-10x caapi batch.

I ran out of spice to work with

I have regular enhanced mint and some 5-10x ( probably like 7x) caapi infused mint. Might just weigh out a 2:1 caapimt bowls worth. I just like making concoctions....