I started translating as I told you last time , now I came back to transifex and I found that 0 strings were translated (in the Arabic language) and there were more strings then before 
Your translated strings should not go all the way back to 0, even though the English strings were updated, though. Not unless, by chance, ALL the strings you translated are among the ones that were changed, but that seems unlikely if you have translated more than just a few.
Either way, Transifex will remember your old translations, and if an English string has only changed a few words during an update, Transifex will suggest your old translation for you. See the "History" and "Suggestions" tabs below the translation text box.
The only reason that the other languages had translations after that change was because I updated them myself. I had pulled down the old translations for any language that had over 5% translated and I just updated those with the new contexts and uploaded them back to the site. Unfortunately Arabic was not one of those languages.