I'd like to know how to create a schedule to reboot or restart cgminer.
You could try CGwatcher. That will monitor it, restart it at specified intervals if required, restart it if it misbehaves, etc.I find the hash rate varies throughout the day, presumably something to do with the bandwidth available in the area. Mine goes from a high of around 220K, falls to around 190K during late afternoon and evening, then climbs back up again. That's on what is supposedly a high speed fibre optic connection; if I switch everything over to an ADSL line (I have both available) it drops by at least a quarter at any time of day. BTC mining on Slush's pool using BFGminer varies in the same way.
If you aren't using your gridseeds in dual mode, use BFGminer - no HW errors and averaging about 355k/hs per device at 850. http://cryptomining-blog.com/1883-download-the-latest-bfgminer-3-99-0-for-windows-with-gridseed-asic-support/