You can find the latest version of the Apptimize SDK here. Once you have downloaded the SDK, unzip and install it.
To update the iOS SDK: Remove old SDK (send to trash), clean build folder (command+shift+alt/option+K), drag and drop the new Apptimize framework into the project (copy into groups destination folder as needed). If you're using Cocoapods, simply run “Pod update” (http://cocoadocs.org/docsets/Apptimize).
To update the Android SDK: Remove the old SDK (delete) from your project, and add the new SDK to the libs folder. Update the library path if needed; in Android Studio check that the build.gradle file contains the right compile path. If you are using Maven, update the Apptimize version in the dependency statement to the latest Apptimize version, which can be found here.