It's not a subscription thing, it's a hours played or hitting a certain point in the story thing. If it got removed once you got into SB, then that's the point you stop being a novice, and know everything that the novice network could have taught you. If you want to keep in touch with them, add them to a friends list, or better yet, form a linkshell with them. If you make a new character, that character will count as a new player, and you will be able to re-enter the novice network as a novice. If you gain the mentor status on your main, you will be able to re-enter the novice network as a mentor.