Welcome to the community!
You can add the repositories again as long as you are the Workspace administrator by following these steps:
I hope this helps, please let me know if you have any additional questions.
Thanks for the update.
The screenshot you share looks like a project tab where you add repositories into the projects and not the Workspace settings.
So can you confirm with me are you trying to add repositories into your projects or in your Workspace settings groups? The steps above are for you to update your missing permission in the Workspace groups under Workspace settings and not project.
The link should be "https://bitbucket.org/<Workspacename>/workspace/settings/groups/"
I hope this helps.