Hello Mate,
You can either use KFCacheExtractor to extract cache files into .rom files (the map file) and save the maps to \Steam\steamapps\common\red orchestra\Maps, so you wouldn't have to redownload them once a month.
OR
You can find your RedOrchestra.ini (\Steam\steamapps\common\red orchestra\System)
and ctrl+f to find the following and change 30 to 0.
[Core.System]
PurgeCacheDays=30
OR
You can manually download the maps from RedOrchestra.pl and save to your Maps folder