When I read 2chan posts I find it helps my retention tremendously to occasionally scan backward through posts I just read and see if I can recall the kanji in reverse order.
For example if I read a post like:>おっぱいの平均サイズがインフレしてるのすごい好き
and say I didn't know any of those words/kanji then I would just spend a little extra time studying them, and move on. Then a few posts later I would scan them all backwards and when I came to this post I would say>好 - su>均 - kin>平 - hei
while at the same time thinking of the meaning of the word the kanji are found in. Bonus points if I can remember the "meaning" of the kanji too, but I don't put too much effort into that.
I know it seems a little silly, but doing things in reverse is actually a really effective way to improve memory in almost anything. Musicians even do this when trying to memorize music by playing the piece backwards or trying to switch the hands they're playing with, etc..
Try it for a few days and I bet you'll be shocked at how poorly you do even on words you think you know very well. It forces you to make sure you're not cutting corners.