But actually this hint will work to force download any purchase on the Mac App Store.
There's an easy method to force a download within the Mac App Store without any tinkering. It seems to be the official method, although I found no description of this in any of Apple's documentation.
So here's how to do it:
- Open the Mac App Store.
- Navigate to your Purchased page.
- Hold down the Option key on your keyboard and click on your 'OS X Lion' purchase link (not on the 'installed' button).
- You see the Lion product page. It should say 'Installed,' but that button is clickable. Hold down the Option key again and click on 'Installed.' If you don't hold the option key it will tell you there's already a newer version installed.
- Enter your login credentials.
- Download.
[crarko adds: I tried this with the Lion Installer and with TextWrangler, and it works as described. You will get the warning if you don't hold the Option key the second time. A handy thing to know.]

