Exploiting the possibility for `:fmt` to be a function it can be done as follows:

    \documentclass{article}
    \usepackage{comment}
    \begin{document}
    \begin{comment}
      #+ORGTBL: SEND table-name orgtbl-to-latex :splice t :fmt (lambda (str) (format "%.2f" (string-to-number str)))
     | 1.000 | 2.000 |
    \end{comment}
    \begin{tabular}{lrr}
      % BEGIN RECEIVE ORGTBL table-name
      % END RECEIVE ORGTBL table-name
    \end{tabular}
    \end{document}