Just some of my thoughts –
Lower the amount of locals that people have to do – alot of families now a days either cant afford to do them or they are involved with other sports/activities.
Make the State Qualifiers an event – pump up the state races, make them something people want to go to.
Make the Championship race worth more than the qualifiers – go with triple points for the final race, make it more of a race at the end. Look at the qualified list and see the difference in the points, most of the riders in first have such a lead that they just have to show up and they win.