If I do archive them first, I usually just drag them to a folder in Finder, zip it and stick it in a general purpose "archive" folder somewhere on Dropbox. I almost never go back into them but just in case, right?
This is probably related to storing the image itself inside the macro:
A better way (once you have finished designing the macro and won't require much tinkering with the screenshots anymore) would be to use a path to the image instead. @iampariah has a tool for converting them, though I have not tried it myself yet. I am not sure if it will work for Display Text in a Window actions, but this thread may get you going in the right direction: