Step 1: Within your "Connections" tab, search for leads that have the value of "2" in the "Incomplete" column.
Step 2: Select all the leads that appear in the Search.
Step 3: Once the leads are selected, press "Actions" and "Fetch Missing Data". Don't fetch more than 100 profiles per day.
For more information on searching, selecting, and running actions on selected leads, see: "How To Filter Leads and Do Actions On Them"