Can the Kai earings(Potara Earings) be used again and again to keep fusing individuals?
The Rou Kaioshin says that you can only fuse once. But the way it's worded it could mean that the person you once was can't fuse with another because you won't be yourself anymore. I.E. Goku can only fuse once because afterwards he won't be Goku anymore.




  Rou Kaioshin: "Also, you can use the Potara only once in your lifetime!"
  
  Goku: "Oh... Did you use it with someone else too...?"


Chapter: 502 (DBZ 308), P1.4

^Above is the VIZ big translation. I have added the raw panel as well just in case you want the Japanese. I don't have a translation for it myself. Sorry.