In פרק ב ירושלים cannot continue in her crying. After so many tears and sorrow, she abruptly stops. She cannot continue describing why she is in pain. She cannot fathom what has happened to her city and the innocent people inside of it. But when it is the מקונן's turn to speak, he encourages her to continue crying. Why would the מקונן encourage this behavior? 

We spoke about the idea in class that when you stop crying it means you stop caring. In this situation ירושלים was sad about G0d's abandonment to her. This means that she cared about her relationship with G0d. But once she stops caring and stops crying for her loss, it means that she has given up on a relationship. The מקונן doesn't want her to give up on the relationship that they had. 

Crying is similar to davening. Crying is a way of communicating to G0d about your feelings whether it is praising or asking or how could you do this. When you stop davening, you stop wanting a relationship with G0d or you don't have anything to ask for. It is kind of like you stopped caring to have a relationship with him when you stop davening. 

We need to remember that G0d is there for us to communicate with Him, so we need someone like the מקונן to come and urge us to cry again.