Castrated male still spraying

Question
I have a 2 year old indoor male rabbit who sprays everywhere in the room where his indoor hutch is placed.  He is a very happy, much loved and settled rabbit who does not appear to get nervous or agitated.  I have tried to curb his behaviour by having him castrated earlier this year but this has not made any difference.  He did not exhibit this behaviour until about 6 months ago.  Any advice on "retraining" him would be gratefully received!  

Answer
He is spraying, or is he just urinating everywhere?  Those are 2 different behaviors.  Spraying rabbits will hit the walls, your legs, etc.

If it is spraying, I will have to do some more investigation on this, since that's not a normal behavior post-neuter.

Kim