Add/remove/update measures, datasources, and columns after publishing .pbix file to PowerBI cloud

I would like to add/remove/update measures, datasources, and columns after publishing the model to PBI cloud. I cannot easily re-upload the PBIX file because there were other reports created off of the dataset than exist in the .pbix file. Also, what if users created their own reports/dashboards based on the dataset. If you remove to upload a new one with the new calcs/measures then you will remove their personalized reports/dashboards.

This makes it a major hassle to go back and edit the data model of an already uploaded dataset. Allow me to enter PBI designer somehow through the cloud, or give me a file that sits in the appropriate onedrive that I can edit (group, personal, or business)