Actually, inside any client, you can do M-x eval-buffer and re-evaluate your whole .emacs.

http://www.gnu.org/software/emacs/manual/html_node/emacs/Lis...

A note: I' be careful though, because depending on how you create your variables, thing can go wrong, I guess: if you-re going to use eval-buffer on your whole .emacs, I'd better use, for example, add-hook instead to add-to-list:

    (add-hook c-mode-hook 'linum'mode)

instead of:

    (add-to-list c-mode-hook 'linum-mode)

Just saying. Have fun with your configs :)