Although the Suzaku team does not provide the scripts which
can extract the latest CALDB files from web site, 
you can download those files by below commands.

$ cd ${PATH_TO_YOUR_CALDB_DIRECTRY}
$ wget -m -nH -np --cut-dirs=1 -R gz,Z ftp://heasarc.gsfc.nasa.gov/caldb/data/suzaku/hxd/
$ wget -m -nH -np --cut-dirs=1 -R gz,Z ftp://heasarc.gsfc.nasa.gov/caldb/data/suzaku/xis/
$ wget -m -nH -np --cut-dirs=1 -R gz,Z ftp://heasarc.gsfc.nasa.gov/caldb/data/suzaku/xrt/

Or, there is another method to access the latest caldb remotely.
You can find the detail description of the caldb remote access at
http://heasarc.gsfc.nasa.gov/docs/heasarc/caldb/caldb_remote_access.html.

When you use "-m" option with wget command,
it checks the timestamp of the files.
So you can download only the updated files
for the second time like rsync.