This code should do it:
> var cursor = db.ClockTime.find()
> while (cursor.hasNext()) {
… var doc = cursor.next();
… db.ClockTime.update({_id : doc._id}, {$set : {ClockInTime : new Date(doc.ClockInTime)}})
… }
I have exactly the same situation as Jeff Fritz.
In my case I have succeed with the following simpler solution:
db.ClockTime.find().forEach(function(doc) {
doc.ClockInTime=new Date(doc.ClockInTime);
db.ClockTime.save(doc);
})