If you choose to leave a lab
So long as the lab isn't full (less than 40 people) and is still set to public (it hasn't been set to invitation-only) you can return to join the lab in the future. You may search for it by name or ID and then tap Join to rejoin the lab!
I accidentally left a lab and now my energy donation has returned to 0. How can I recover that energy?
Unfortunately we have no way to help you recover your donated energy, nor can we restore lab leader status. When you leave a lab, a notice will pop up asking for your confirmation, reminding you that any record of your donated energy will be lost. For this reason, when you confirm and leave the lab you are also agreeing to these conditions.
We appreciate your understanding. Thank you.
If you've been expelled from a lab by the lab's captain
The captain may decide the duration of expulsion (1 day, 1 week, 1 month, or unrestricted (return at any time)). You must then wait for this time to elapse and ensure the lab is both not full and still set to public to be able to once again search for the lab and rejoin it.