Typically, LW will catch new theme files promptly and you shouldn't need to worry about it. In rare cases—if you're working on a custom module in /client/modules, say—you may want to try and force LW to check for new files right away. This is possible using either or both of the environment refresh URLs:
If your module utilizes both public and private realms, then both may be necessary, otherwise only one would be. These URLs are also handy to have LiveWhale refresh itself after an upgrade, especially if you use a non-LDAP SSO for LiveWhale authentication.