Renew pppoe IP

Hi,
My ISP provider sometimes gives to my Mikrotik a private IP in the public IP. It seems like they have no more publics IP, and they put me under a router they have(I talked with them). The problem with this is that when that happens, I can’t use dynamic DNS because it redirects me to that router and not mine. I did a script that checks if my public IP is private, and then turns off and then turns on my ether1 port to renew my public IP and it works, but I want to know if there is some way to not to turn on and off the port(it doesn’t seems very secure) and use something like “renew”.
Thanks you.