setlocal indentkeys+=[,(,{,),},],&,=item,=else,=fi

begin{itemize}
  item <CURSOR>
end{itemize}

begin{itemize}
  item
    <CURSOR>
end{itemize}

begin{itemize}
  item
  item <CURSOR>
end{itemize}

snippet it "Individual item" b
item $0
endsnippet

begin{itemize}
  item
    item <CURSOR>
end{itemize}