Here are some options you could use:
Formal:
* E komo mai hou (literally "come in again")
* E hoʻokipa hou ʻia ʻoe (literally "you are welcomed again")
Informal:
* Aloha hou (literally "new hello")
* E hoʻi mai (literally "return")
The best choice will depend on the specific situation and your relationship with the person you are greeting.