Amara can be a short form of Amaranta, the Anglo form of Amarante. Amarante is derived from Greek amarantos "unfading" (thus having a related meaning to the Indian version).
More out there, but still conceivable is that Amara could be a short, altered form of Amardad, a feminine Persian name. Amardad's the modern form of Ameretat, meaning "immortality" in Avestan. Ameretat was the name of a Persian goddess of plants and long life (hence, presumably, her name's meaning), and Ameretat is also the name of a month in the Iranian calendar.
Amara could even be a form of Amariah, a masculine Biblical name meaning "Yahweh has said" in Hebrew.
I don't know about any German, Arabic, or Spanish meanings, sorry. Are you quite sure you're checking reliable, non-"baby name" sites/books?
Miranda "Multiple exclamation marks are a sure sign of diseased mind" -- Terry Pratchett
Proud adopter of 15 punctuation marks. Check my profile for their names.