I think the avast installer prompts you to reboot following a repair anyway
No. Neither the "fix it". In some
few situations, the reboot won't be needed. In most situations (where a "problem" is really there) you need to reboot.
The reboot sometimes is needed for items that are part of the initial process of Windows booting. Sometimes there are alternative methods, but usually a reboot is much simpler to explain in the forum and faster to apply. Sometimes there is a need to update, which is also done after a reboot. Sometimes, there is problem with some file not being "released", so it can't be changed / updated until a reboot. Sometimes there is an issue with the display (either with the UI of avast, display drivers and so on).
Hence, in the vast majority of cases, when the user already says he is not seeing any change after these type of actions, first reboot, and then wait about 10 minutes (after the reboot) for all the boot processes to finish (including avast rootkit scan and automatic updates).
Instead of investigating which of all possible situations is making problems, reboot and then it is possible to narrow down the problem (if it even continues to exist).