For Agoda, Hostelworld and My Allocator both rates and availability are updated automatically from Sirvoy per default. Seasonal price changes and spot price-updates are also sent if supported, read here for more info about supported price change updates.
SEMI AUTOMATIC UPDATE
Sirvoy also supports automatic sendings of price to booking.com and Expedia, but you need to activate that feature yourself under "Settings > Channels > Booking, and Expedia > Send rates automatecally". Otherways you need to manually update prices each time you change any regular or seasonal price in Sirvoy under Settings > Channels > booking.com or Expedia.