If you have downloaded the game and you have extracted the files, there is a folder named "HELP FILES." Inside is a text document named "Save Transfer." It has instructions in how to transfer your save files from he previous version.

I have copied pasted all the text from the document here:

If you're playing on the PC or Android version of Zombie's Retreat, you can transfer your saves across builds as long as it is compatible.

WINDOWS:

Open the folder of your OLD Zombie's Retreat game and look in the 'save' folder.

Open the folder of your NEW Zombie's Retreat game and click the 'www' folder then open the 'save' folder.
    -If you do not see a save folder, simply create a new folder here and name it save

Copy EVERY file in the OLD 'save' folder and paste the contents into the NEW 'save' folder.

Load up the new copy of Zombie's Retreat and the game should read your save files!

ANDROID:

(Android build is a little more tricky/situational to properly transfer)

DO NOT uninstall/delete your old version of Zombie's Retreat.

Install the new update. (Requires roughly double the file space on your phone in order to unpack & install ToP).

Your device should recognize matching games and will automatically update & transfer save files accordingly.

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When new builds make changes to old save files to help keep them updated, it's done so by standing outside your house.

Make sure to step outside for the update to fully work before trying the new contents of a build.