I installed an application using Personal Package Archives (PPA). I installed the application by adding the "unstable" PPA, and now I want to switch to the "stable" PPA. So I removed the "unstable" PPA, and added the "stable" PPA. After doing the apt-get update/upgrade, it didn't detect a change, and the application is not getting reinstalled to the "stable" PPA.
How do I trigger apt-get to re-do the install?