I mean theres not a limit to how many times you can apply for an admin position but at the same time theres also not a limit to how many times yuki or merpy can deny you, just wait a couple months and you'll be fine
Depends on the reason you were declined and how you look to improve upon it I suppose. Like Pete said there is no limit but if you were banned recently for a big thing don’t expect a different result. Just wait until apps open again and judge yourself if you think they will be more forgiving of your reason of denial.
In my experience, it's best to wait until the next time applications open as it gives you a "fresh slate." I've seen you on ff2 and I think you have the potential to be a pretty good mod/admin, try again in the future if you did apply this time around, if apps stay open for around a month, then you can always try again then.