Sometimes, we do have the issue of your review tab disappearing from your site. When that happens, you can do the following:
1. Go to your Kudobuzz account
2. Go to the customize widget page.
3. Scroll down and hit the Save Settings button
4. Reload the page and watch the preview box to see if the tab appears.
5. Go to your site and reload the page.
Alternatively, you could go to your Manage reviews page, Unpublish a review and the republish it, then reload the page. Then, go to your site and reload the page as well. You should see your Review tab back on your site.
Note: This works for all other forms of review widgets as well (full-page, slider, product review widgets. What you have to do is to go to the customization page for the various widgets and then hit the save settings button)