I am looking for a word/adjectif/adverb that means that something is happening again and again after a fixed amount of time. I would be tempted to use "regule", but that word is unclear since it can mean "according to the rules".
2 Answers
I think that perioda is what you're looking for.
You could also use the Esperanto ability to create new words, for example - regulrevena, regulalvena, denovfoja. It depends on context which one is more suitable for you.