How to preserve a config.json file when reinstalling electron app?

I have an electron app that uses a static config.json file to hold individual client connections. When we reinstall the the app, say to a newer version, the file gets wiped in c:\programs{appname}. Is it possible to retain this static file on reinstall somehow? We're using electron-builder for the build.

I have been attempting to edit the nsis settings in the package.json file, our current set up is:

"nsis": {"oneClick": false,"perMachine": true,"artifactName": "${productName} Setup.${ext}","uninstallDisplayName": "${productName}"}