if you always have the same "dimension" consider using classification!
example: assume your "exclude" is based on operating system and browser, different each month.
add a new prop to each server call like this
"YYmm-{useragent}"
now you can use classification to set a "exclude" flag "badTraffic" for the desired month/browsers.
this solution allows to use a simple segment (just exclude the "badTraffic"). all you need to update is the classification file - and this can be done in advance!!!