Just disable any URL filtering (DNS, proxy, deleted update folder you have to recreate, etc.) and just hit the official update button.
if you have haxchi, updating will have no effect at all on your current hack.
If you have CBHC, and you are on a non european console, it's working fine and you'll have no effect on your current hack either.
If you have CBHC and you are on an european console, the 5.5.3 update replaces the WiiU system menu to add a new option for "GRPD opt out" (or whatever its called in your country). updating the system menu removed the auto-boot information from CBHC.
It does not delete CBHC (the NDS channel replaced with CBHC), it replaces only the autoboot information.
After the update, put CBHC installer back on your SD card and launch the "do not touch me /!\" channel to launch CBHC manually, then select "Homebrew launcher" option from the boot menu. Once in HBL, launch the CBHC installer to re-set the autoboot option.
After the update, you can re-enable your previous URL filtering choice to prevent random future updates.