In these period, it is normal that you still can't see some dates of the
next season.
This happens, in particular, for the Circuits that host the national and
international top level competitions, because they have to wait for the
international racing calendar to be organized, collaborating with the other
race tracks.
However, you can secure your reservation in next year's events, by
booking the option to choose the date later; this also gives you the
flexibility to change the date after the booking, as per the conditions of
the package you choose.
You will soon see the next year's dates, usually they are online by first
half of December.