Meteor Cookbook may have some useful info:
Database Management for Meteor/Mongo Apps
Your mongodump/mongorestore should be preserving _ids. If it’s not, something isn’t configured correctly. Are you dumping to .bson data? If you’ve walked around the bson, and are using the json file options, that could cause a reparse of the data.
If none the mongodump/mongorestore recipes in the cookbook help, try using the db.copyDatabase() function. It’s what to use in production devops situations, where you want to hot-copy entire databases from one running instance to another.
db.copyDatabase('staging', 'meteor', 'localhost');
The only caveat with db.copyDatabase() is that it expects itself to be run on port 27017. Since the meteor database runs on port 3001, you won’t be able to copy from your production database to it. Rather, you’ll need to set up a separate mongodb instance and then point your app’s MONGO_URL environment variable to it.