My approach is to simply repeal an existing act, the one which bestowed citizenship on Indians in the first place.
Now that I think about it, we don't even need to replace it. All current Indians in our borders are already American Citizens, so the act no longer serves any purpose.
We can repeal it now, and it won't even affect American Indians, it will only affect Mexican/Central/SouthAmerican and Canadian Indians.
My point here is, What is the court going to say to that? You can't argue it's Unconstitutional because it has an established history. It would be too great a departure from the truth for even the lyingest of courts, I hope.
It would be using the explicit words of the 14th against the Courts, and they can hardly say the "penumbra of equality" they see in the 14th can override the clear and explicit words denying such citizenship.
Too bad we can’t throw out several dozens judges off the bench to let them do honest work.