From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
New Planet Namek (新 ナメック星, Shin Namekku-sei) is a planet in the North Galaxy.
New Planet Namek was the second homeworld of the Namekians. It was similar to Planet Namek due to the green water and blue grass. This planet has been mentioned or seen in Dragon Ball Z: The Return of Cooler and during the Cell Games Saga, the Kid Buu Saga, and the Baby Saga.
Dragon Ball Z
During the Cell Games Saga, Son Goku used the Instant Transmission to travel to New Planet Namek and find a replacement Kami for Planet Earth. Dende was selected and happily accompanied Goku back to Planet Earth.
In Dragon Ball Z: The Return of Cooler, Goku and some of the other Z Warriors battled Cooler, his Cyclopian Guards, and his Meta-Cooler clones on New Planet Namek. Cooler had been attempting to use New Planet Namek as fuel for the Big Gete Star.
Dragon Ball Online