I assume you have a query somewhere and maybe you're using the EntityQuery component. You need to reload data after a save operation (not done automatically) The refresh method on a query does that.
Is EntityManager is EntityQuery component?
I use EntityManager to get a list of result for DataModel.
I'm a newbie to SEAM FW, so please teach me what to do in details
Without any code it is difficult to understand what you have build. If there is a component which extends EntityQuery (or maybe allValue is factory??). All you need to do is call the refresh-method, which will trigger the query again.