Formal:
* A hui hou: This is the most common and formal way to say goodbye, meaning "until we meet again."
Informal:
* E komo mai: This literally means "come in" but is often used as a way to say goodbye, implying "come back again."
* Aloha kakahiaka: This means "good morning" but can be used to say goodbye with a wish for a good day.
* Aloha ahiahi: This means "good evening" and can be used similarly to "aloha kakahiaka".
* Aloha auinala: This means "good afternoon" and can be used similarly to "aloha kakahiaka".
More specific to the situation:
* A hui hou ma kahi e: This means "until we meet again, somewhere else."
* A hui hou i ka la e hiki mai ana: This means "until we meet again on another day."
You could also simply say Aloha! as a general goodbye.
Ultimately, the best way to say "goodbye-till we meet again" in Hawaiian will depend on your specific context and relationship with the person you are speaking to.