Where you have to go will be determined by where you live. If you live in C.A.B.A. (Aka Capital Federal) it looks like you have to go to the Registro ay Av. Hipólito Yrigoyen 952, if that is the only location that can make the change of address and issue a new tarjeta for foreigners even if they have permanent residency.
Here is the website:
https://www.argentina.gob.ar/dni-para-extranjeros
Since you already have permanent residency it looks like you may be able to do this closer to where you live in C.A.B.A. at one of the locations you can find by scrolling down the page and clicking on oficinas de Renaper.
That will take you to:
http://turnos.mininterior.gov.ar/turnosWeb/
The website does not indicate that a certificado de domicilo is required (at least I did not see that) but that doesn't mean it isn't! How else can you prove your new address?
Assuming that you'll need one, I suggest that you get the new certificado domicilo from the police before you make the appointment (turno).
If you live in Buenos Aires (aka La Provencia de Buenos Aires) you will have to go to the delegación o centro de documentación closest to your domicilio.
Here is the website:
http://www.gob.gba.gov.ar/portal/index.php
After you go to the site click on DNI/passport
Then click on nuevo ejemplar, then donde puedo realizar el tramite, and then click on turnos online.
Then follow the prompts to reserve your turn and make the payment online. Be sure to print the receipt for the payment and take it with you when you go to the delegación o centro de documentación to get your new DNI with the desired change of address.