Just use the svnsync command.
First, create a fresh repository on your home machine.
svnadmin create c:\backuprepo
Or on Unix:
svnadmin create ./backuprepo
Next, create a file named pre-revprop-change.bat:
echo exit 0 > c:\backuprepo\hooks\pre-revprop-change.bat
Or on Unix:
echo -ne '#!/bin/sh\nexit 0' > ./backuprepo/hooks/pre-revprop-change
chmod ugo+x ./backuprepo/hooks/pre-revprop-change
then, initialize the sync:
svnsync init file:///c:/backuprepo https://url/of/your/repository
Or on Unix:
svnsync init file:///Volumes/volumelabel/backuprepo https://url/of/your/repository
After that, you can simply run
svnsync sync file:///c:/backuprepo
once a day or so, and you’ll get only those changes which are not yet in your backup repository. The first time it will take a while, but after you’ve synchronized your backup repository with the real one, it will only take a few seconds to sync it because only those revisions that are new need to be synched.