If your dashboard is still showing surveys that you have already done, or that you have tried to participate, then it is possible that somehow you have left those surveys incomplete. In those cases, please make sure to click the final >> or "Submit" button on the survey screen. More details here.
Note that there are some surveys that only allow a single access. This means that if you have entered the survey before and left it incomplete, you will not be able to participate again. In those cases, just ignore the survey (it will disappear from your dashboard in a few days, once it closes for all participants).
On the other hand, if you click on the REFRESH SURVEYS button, and there is no new surveys, this is because there is no new surveys available for you. Remember that the frequency of surveys varies; more details here.
A survey disappears from your dashboard when:
As soon as we have new surveys, there will appear in your dashboard, so stay tuned! and thanks for your interest!