Best way is just to create a new SUICA. To do this (unless something's changed in the last year), you need to set your iphone's region to Japan and let it restart. Once it's restarted you can add a SUICA to it and then fund it with a credit card up to 20k yen (as of last week visa cards weren't working as mentioned above, not sure if that's changed). Then just change back from Japan region to US region.