Well, there is no parameter to control this behavior. The Link Alive message is sent automatically every 60 seconds, and that's hard-coded in the 3CX source code....
The log you should check is the "3CXHotelModule.log", which you can download from the 3CX Console > Dashboard > Activity Log > Logs button > Instance folder. Ensure that you have enabled verbose logs from the 3CX Console > Dashboard > Activity Log > Settings.
Do you see any error in this log? Maybe something happened and the working loop was aborted?