Is there an opportunity to get everybody in the same physical location for a day? Either way, maybe it would be good for you to have a clear the air session, communicate vision/direction/expectations, allow them to communicate their issues with you etc. In my experience as a manager, when I see team performance start dipping etc.. then I start to identify why and maybe introduce new ways of doing things, i.e. keep reinvigorating the team. Communication is vital in your team; have short audios on a daily basis if you can afford it. Keep track of issues. Inject some spirit into your team.