There should be a small red circle in the bottom bar that lets you re-sync to the firewall or in the "file" menu choose "Refresh ASDM with the Running Config..." I do have an issue with the ASDM logging droping out after about 10 minutes. The only way I can get the ASDM logging back is to close and relaunch the ASDM. I am assuming that I hit my buffer limit.