Cross-posting this from the off-topic forum because I think it is potentially more on-topic than not and might be useful for some:
http://animagnum.com/projects/spine/SpineScale.zip
I made a quick and dirty tool that will adjust an exported JSON file in case you need to scale an entire animation to work with different sized assets. The swf will require some form of Flash Player in order to run as it currently does not work when run through a browser. The tool looks for a file named skeleton.json in the same directory as the swf. You can easily rename a file and then change it back when you're done. Enter in the scale value you want to multiply the object by and then click the scale button. You will be prompted to save a new file so the original remains untouched.
Here's an example of how it works:
I created some assets and an animation at one scale (1x) but needed to resize the animation for 2x. First I made 2x assets in Photoshop and then replaced the original assets in my /images/ folder. Then I used my tool to modify the JSON file and used a scale value of 2. This process multiplied all of the relevant values by 2 and then saved a copy of the original JSON. Back in Spine I clicked "Import Data..." and selected my modified JSON file. Then I pointed it to the directory with the resized images. This resulted in doubling the size of the animation I had previously been using.