If you still qualify as a "new adventurer" (which it looks from your Lodestone profile like you do — it lasts at least until you reach Stormblood), you just need to ask a mentor to re-invite you if you want back into the Novice Network.

Finding other people to chat with as well is still a good idea, though. Even if your "new adventurer" status hasn't worn off yet, it eventually will, and then you won't be able to get back into the Novice Network without becoming a mentor, which can take a while. So stay on the lookout for some friendly linkshells to join, or maybe another FC.