Remapping Table to source view

I have a datamart we created to host a few tables. We connect the tables to the source views, set them up to a schedule to refresh the data and all works. Now, we had to change the source view after connecting it, one of the columns was deleted and a few new ones added. So, now every time we try to refresh the table, the refresh fails. We checked and realize we have to re-map the table to reflect the new columns. I have tried to do that in the "Transform Data" but have not found how. Any ideas or documentation I can read?