Hello Jorge -
No, Lansweeper does not replace a real-time monitoring system such as PRTG (Which, in my opinion, is a great product). Rather, it compliments a monitoring system.
Lansweeper is more of an asset inventory system and a systems compliance application. It generally by default scans items about once a day. Yes, you can make it do certain things that a monitoring system can do, but it is not designed for it, and is not as efficient by far.
It will not tell you if you lose connection to switches or servers, etc.
I highly recommend you read through the product details, as it is a swiss-army-knife product that brings a whole lot of value to a company or organization.