If you get it remarked you run the risk of getting an even lower mark than before cus they could take marks off. Unless you're taking Chem onto A2, what's the point with being so bothered about it? And if you're taking Chem onto A2 then resit would be better cus then you can try and get a solid B instead of a low B. A low B does not put you in any advantage really at A2, but a solid B would. So if you're gonna spend money on it, it might as well be the resit, and that way, you cannot get any lower than what you have right now cus the best marks out of the original and the resit would go through.
And if you're not taking it to A2, what's the point in getting so hung up over it? Btw, at AS, I also got 209/300 lol. My teachers predicted me a B. I got a C in the end at A2 - mid C. I didn't work for either year though so I'm happy. And I applied for 5 different science courses lol, all of which were in the field of Biomedical Sciences and I got 5 offers. So that C at AS will not affect you as long as you have other good grades and a good PS and good interview, if they offer you one.
I read somewhere on here that most do, it was yesterday in fact. So who's right, you or the other person?
EDIT: That came out as vaguely vicious, sorry, I'm obviously in a bad mood.