That's why we keep backups.
Most of the time, the grub update will recognize Windows and add it. Occasionally, it'll miss. It shouldn't be too hard to copy stuff though using a graphical editor (or a text one either).
In linux, there's a trick about copying text:
1) Highlight the text you want with the mouse cursor (this copies the text)
2) change to the other application you want to paste it in
3) Middle click to paste (on my two button mouse, that's press both buttons at once).