When you have a published treatment running to your ads, you can still edit anything about the designs that make up your treatment.
Any edits you make will generate the following a badge on the design:
This badge denotes that edits (including filter adjustments) were made to your design.
When you're ready to set the edits live, go to your output feed and click Publish Updates. Marpipe will then write a new version of the feed that includes the updated design to be picked up by your catalog on the next request.