The final thing to try before redying is to use saddle soap and water, but tons and tons of fresh clean cotton cloth to soak up the dirt with, changing cloths constantly. Sometimes the problem with cleaners is that they loosen the dirt, but you don't get it off the leather... all you do is rearrange the dirt. So clean a small area and keep cleaning it with saddle soap and cotton cloth. Remember that you want suds, but not to soak the seat....

Odds are that you will end up redying however if it's more than a few years old. Good luck!

If you've tried cleaners and they're not helping, the most likely culprit is the dye. Leather by nature is a grayish color--the white dye only sits on top of it. As the leather ages and is used, the dye flakes away in thin layers.

Make some phone calls to local upholstery shops to see how much they'd charge for a redye. It shouldn't be too expensive.