This is the 129th most frequent Croatian word.
opet
"Opet" means "again" in English.
Here, 'opet' is used to indicate the repetition of an action, signifying that the forgetting of the key has occurred before.
Opet je zaboravio ključ.
He forgot the key again.
In this context, 'opet' conveys the return to a previous state or action, describing the sequence of moving upstairs after going downstairs.
Siđi dolje pa opet idi gore.
Go downstairs and then go upstairs again.
Here, 'opet' is used to suggest a recurring action, meaning the act of talking will happen again as it did before.