How to not lost plugin translations when updating

Hi, guys...

Every time I update a plugin I need to copy again the stored .mo file of the translation in to the languages folder of the plugin... this work's but is really tired to do it each and every time that I update a plugin in my clients sites...

do you know an other way? a way in wich the new plugin update don't overwritte or delete the translated mo file...

this will be really really help full.

Thanks!