Hi Ethan,
you are added the additional fields at DSO and INFO CUBE. if you want the historical data do full load.
delete the entire the data form DSO and CUBE then load with full.
selective deletion for specific records deletion and first decide the which records your deleting then do selective deletion.
select you cube -> go to content - select selective deletion option.
better approach delete the entire data and load again DSO to info cube.
Thanks,
Phani.