If your site statistics indicate that you are receiving a good traffic volume, but most visitors leave within 30 seconds, it's time to try something new.
The key is to experiment...and keep experimenting until you see a favorable shift in your site's "stickiness." This can be measured by sales conversion or simply a positive change in the duration that typical visitors spend on your site. Look at return visitors too - the more the better.
But the bottom line is that a Website is dynamic. You always have to be adding new content and adjusting your offerings, layout, navigation, incentives and attractiveness until you find a formula that works. That's why it is so important to carefully review your site statistics on at least a weekly basis.
Hint: Make small changes and give it a few days to see if the change is having a positive effect. If not, try something else. Keep experimenting and sooner or later, you'll find the right mixture that puts money in your pocket!