wow!! you've lived in America for a long time = Wow! Ang tagal mong tumira sa America.
You've lived OR you HAVE LIVED is in past participle, which indicates past or completed action or time hence you should use, "tumira (lived in/at)" not "nakatira (living in/at)".
Wow! Ang tagal mong nakatira sa America. = Wow! You've been living in America for a long time.
Wow! Ang tagal mo nang nakatira sa America. = Wow! You've been living in America for a long time already.
Hope this helps. ;)