[Answered ]-Every time I use .update(release_time=initial_time) i get an error 'int' object is not iterable but if I change it into .all() it works just fine

Update returns a number of records updated by a query. (not exactly updated, but matched a filter clause – more info)
You may just query records once again after update..

Loaded.objects.filter(lap=id).update(release_time=initial_time)
load = Loaded.objects.filter(lap=id).all()