Downloading two copies of the Yosemite public beta Apple granted me access to the Yosemite Public Beta, and I successfully installed it onto my Macbook Pro. I now intend to replace my Macbook Pro's HDD with an SSD drive and I want to make a clean install of Yosemite onto it. I tried accessing the OS X Beta Program page that gave me the code I redeemed the first time and clicked the code, but the App Store says it's not possible to redeem it again.

I have access to the iOS Developer Program, but it doesn't seem to allow me to download a build of OS X  Yosemite.

I tried searching my computer for the install program but it's now gone, possibly removed by Yosemite itself once it had been successfully installed. Not having access to the software and having no way to download again through the same procedure, I'm wondering if there's any way to make a clean install of Yosemite now that I've already installed it.

Is there any way to recover the software (e.g. could it still be somewhere on my disk?), or to download it again?
If you go to the App Store and select "Purchases" tab while holding Option also called the alt you should be able to re-download the installer.  Then it will show up in the Applications folder again.