Honestly, one fairly simple way to increase interest, or sustain interest in between events/meets, is to do like the NCAA or ESPN or whoever just ran the brackets for March Madness
Create an app anyone can download. List the competitors in each event. Allow viewers to do anything from picking the winner, top-3 or even first through last. Keep track via the app where each viewer is in terms of their pick accuracy. Can be done for a single meet or the entire season.
It doesn't even have to be for money. People just like to make predictions and see if they are better at it than others. Make it bragging rights only if need be.
These sorts of things are done in every major sport. It's not rocket science.