Firstly: stop playing so hard for so long.
Secondly: the 'standard' treatment to harden up finger tips is to dip them for half a minute in methylated spirit. It won't work wonders, however, if you're punishing yourself with over-zealous practise.
Be assured that, as with most things, the fastest way is to go slowly. Practise, of course, but in sessions of, say, fifteen minutes, with a break, then another, then a break. Little by little (weekly..?) increase the session length by five minutes. This will give your fingers time to build up the toughened skin.
Hope this helps.