To get this straight, you want a command that puts you back into the active game that you disconnected from? That would be very much abused by players, unfortunately, so I don’t see it as something we’d consider. For example, people may intentionally disconnect to avoid dying, then simply rejoin.
Regardless, this seems to have been suggested before, so I’m going to go ahead and close this duplicate. Please use the search button to check for existing threads before you make a new suggestion, as you can go and add your thoughts on one we already have 
And welcome to the forums!