You get to decide
There's no rule against resurrecting old threads, nor against starting a new thread when an older one isn't relevant to your purpose.
The decision should depend on what you think will make the thread more useful for those who read it. An older thread may have the wrong context or contain obsolete information so a new thread will make more sense. On the flipside, the old thread may still provide the background for what you want to discuss, report, or ask.
Example: I had to weigh those choices myself the other day myself when I reported the latest
Turing Award Winner. Even though the thread is old, I thought the few of us who like to read about the heroes of computer science history would find it more interesting in the context of past winners.
So the choice is up to you. And what will go wrong if you make the wrong choice? Nothing serious.
If the moderators consider an old thread and a new thread to be duplicates that ought to be a single thread, they'll merge them, but they won't treat it as breaking the rules. They'll simple be making the forums as useful as possible for other users. It's less common that they'll split a thread into two parts when new posts are made; they'll typically do this only when the new post is really about something very different, and the user was simply confused about how old the thread was or didn't know how to start a new thread.
You shouldn't worry that somebody will tease you for posting in the old thread if you have something new to add to it, e.g., a new solution to an old problem or the return of an issue from years past.
If you are worried about starting a new thread and being teased for not searching first, you can post a link to the previous thread in your new thread, especially if it helps distinguish the old topic from the related new topic.