My question is more of Android Studio tool for Compose than Compose itself. The Compose Preview Window is not updating, what are possible ways to fix it?

build?

Having the same issue in 2020.3- sometimes just building the project fixes it, sometimes restarting AS fixes it.

Thanks for your suggestions guys. Although rebuilding or restarting android studio does work but the issue presists and I think its impractical to have to rebuild the project anytime I make a single change for the preview to update. Any more permanent solution?

There are some open issues that talk about the preview. You may find one that explains your problem. https://issuetracker.google.com/issues?q=componentid:612128%20status:open%20preview

Sadly in 2020 the first law of computing still applies: reboot, see what happens.