Why don't Publishers market their games a month after release?

[Severance]

it seems that publishers only (Hardly) market a game before release and when it releases they make a lame commercial for launch , then these ads on the internet stay for a week and then suddenly the game disappears.

so why?

as for another question for that matter , why doesn't publishers market a game if it didn't do well to make people AWARE of it? its like they WANT their games to sell like crap. (i am looking at you SCE + White Knight Chronicles) only advert i saw about that game was on VGChartz.