In MeetVIP, you don't have to input your athlete roster every single time you join a meet. Your athlete roster is linked to your gym profile instead, so you can just load it up whenever your gym enters a meet.
You can input your athletes manually or by importing from the USAG or USAIGC web site. You can begin by clicking on the Manage Athlete Roster link on the left sidebar menu, below your gym name. This will take you to your Athlete Roster page for that gym.