Unfortunately, there is no shared scope across activities. Upon entry into each activity, the ECMA/Javascript engine is started. Upon exit from the activity, the engine is stopped. To overcome this, use System.setGlobal/getGlobal.

Rusty Fobe has been nice enough to upload some utility scripts in the files section that let you save/restore object trees. Also note that this is basically what JSON (Javascript Object Notation) does as well.