[Xymon] How to make log errors repeat for an hour

I am trying to capture BMC alerts, and it works, but there is only one alert email, and on a busy day it could be missed. I saw a reference to making an alert last longer, similar to what is done for Windows Event logs ( they last an hour ). How do I do this  for normal log monitoring as well as any custom checks.

Thanks !

Michael Resnick Sr. Systems Eng.