Unfortunately the only way I can think of to really get rid of it would be to introduce points deductions. Harsh on the players who rarely have anything to do with the racism these days, but I imagine it'd fix things in the crowd fairly sharpish - imagine making a racist chant at a match only for your team to then get docked points and get relegated/miss out on the title, and knowing you were personally responsible! Similarly, if you're sat in the stands next to some guy doing it there's then a much bigger incentive to turn him in. Basically encourages collective responsibility throughout the entire club. As I say, it could be seen as harsh, and there would probably be a 'bedding-in' season or two with teams being punished left right and centre, but I can't think of anything that would work more quickly or more effectively.