HTTP is a stateless protocol. Whenever someone views your page they will get whatever your program outputs. If you want to display a running log of lines, you will need to store the information somewhere (a log file usually) and then display it.

Update: After messaging with dragonchild for a bit, I think I need to clarify what I think the OP is asking.

From what I can undertstand, the OP has a subroutine that generates new data each time it's run. This information is displayed on a web page. This is where I'm a little confused. Does the OP want to display the old information in addition to the new information, or just display the new information, but keep a copy of the old information somewhere else?

Maybe I'm just not thinking too well today, but dragonchild has me questioning what I'm reading in the question. :)