[AJC]

Since population grows at such a slow rate it is worth saving the population - build cheap transports; engines - cargo containers and vehicle control components.
Then 2-3 turns before the star goes nova move the population out of the system and use the abandon planet button on each planet. At the least you can scrap the facilities as you abandon the planet and get the resources for those worlds - as for the refugees, move them to other worlds that need population or rebuild the system with stellar manipulation then recolonize and then repopulate the new worlds.