Using should in as sentence is suggestive as to an action.
You should help your mom. She can't do all the work.
This is fairly generic. It can be used to suggest a present action (something you currently may need to be doing), or be suggestive of a future potential action.
For example, the mother may be picking up the kids clothes off the floor and the father is informing to the kid, that he thinks the kid should be assisting his / her mother. He is not directing or telling the the kid to go assist his / her mother right now (or even in the future), it's only a suggestion as to an action the kid can take.
You should be helping your mom. She can't do all the work.
This is little less generic as this applies to something happening currently (present).
For example, here the father's suggestion is a little more specific as the father is suggesting the kid go help his / her mother now, instead of whatever the kid is currently doing.
... so yes, "should be" adds a small amount of urgency.