Doesn't it cost money to resit who year?
How about doing your A2's and getting best grades possible in them, and also resitting some AS modules. If your still unhappy with your grades, then you can resit you AS only as you would have good A2 grades?
Instead of you resitting your whole year now and how about you mess it up again, then what you going to do?
So take my advise move onto A2, get best results in them and do some retakes of AS modules then see if you bumped your grades up, if you havent then do AS year only.