Apologies. I misread your question and thought you wanted another word for what people do when they ask the same question twice.
Yes, "bumping" is a common and very annoying way for people to push their own post to the top of a thread in any forum. Some people at least have the decency to pretend that they have made a valid extra comment by adding some information or an extra question in order to push the post up. Others are more brazen and actually simply write "BUMP" as a comment and post it.
However, that would not have fitted your original question. You said "When people repeat their threads because they are not satisfied or got the required information, moderators
use one word and ask them to do that instead of repeating the thread. What is that word?"
Moderators don't ask people to bump threads. They ask them not to bump threads and not to repeat their question either. They usually ask them to be patient and wait for a response.