Short Answer 
To manage and update your Maven project in IntelliJ IDEA, first open the Maven Projects tool window. Then, reimport your project or update dependencies by right-clicking on your project, and for a comprehensive update, execute Maven goals like clean and install in the command line area.
Step 1: Open the Maven Projects Tool Window
Start by launching your project in IntelliJ IDEA. If the Maven Projects tool window is not visible, you can access it by navigating to the right side of the screen or by selecting View > Tool Windows > Maven Projects. This tool window is essential for managing your Maven projects and their dependencies effectively.
Step 2: Reimport Your Project or Update Dependencies
Within the Maven Projects window, locate your project or one of its modules. Right-click on it to reveal a menu, then choose the Reimport option to refresh the project settings. Alternatively, you can also update dependencies by right-clicking on the install or clean install goals under Lifecycle and selecting Update Dependencies. This ensures that the latest dependencies specified in the pom.xml file are fetched.
Step 3: Execute Maven Goals for a Comprehensive Update
For a deeper and thorough update of your project, you can execute the Maven goals like clean and install. To do this, type these commands in the command line area of the Maven Projects window and execute them. This process will remove previous builds and compile your project with the latest dependencies, ensuring everything is up to date.