How to add new table to existing database code first

Just create your new table as a model and add its entry in DbContext class

something like

 public class TestingContext : DbContext, IDisposable
{
    public DbSet<CallDataRecord> CallDataRecords { get; set; }
    public DbSet<Attempt> Attempts { get; set; }

    public DbSet<MyNewModel> MyNewModels { get; set; }

Then add-migration and update-database