When updating the congress member data we need to get a new data csv. Use the current or past csv as a template.
congress.csv will always be the current data to import.
Archive the old csv by changing it's name to congress[MM][YY].csv
See the status of the congress_member migration
drush migrate-status congress_member
Remove all existing imported data
drush migrate-rollback congress_member
Import the new data from congress.csv
drush migrate-import congress_member