I'd consider continuing previous stories, but, they are old, like a few weeks, and would get non-stop posts about what a thread necromancer I am
Don't worry about that. I recently restarted a story that I hadn't updated in a
year. If it's your story you're Necromancing, no one will care, as long as the Necromancing post isn't just a bump.
I agree with DarkNova on just about every point.
Then again, I struggle with keeping stories going myself. I tend to maintain several active projects in several different fandoms + original works, all at once, and have dozens of novella-sized unfinished stories on my harddrive. When I feel the itch to write, I can just pick which one I want to work on depending on my mood. Sometimes, I'll go back to stories I started years ago and add a page, or just edit for awkward phrasing. Keeping up your literary attention span can be very difficult, and there's no point to work on a story if you feel you're not getting anything out of it.
Nonetheless, a track record of giving up is not something you want to build, especially not in a place where fanfiction readership is already fairly low. Zalphon, I suggest that the next story you post be something you can really commit to. Nurture the characters and make the setting real for yourself. Make yourself
need to finish it. And plan at least a skeleton plot so you have something to aim toward. This way, you won't feel so lost in writing on a story idea thought up on the literary equivilant of a whim.
So, as DarkNova said, it's your call. You can revise a previous story (we won't call you for Necromancy, promise) or you can start this one. Whichever you do, make it one you care about and can get into. That way, we can too.