How to force IntelliJ IDEA to reload dependencies from build.sbt after they changed?

You can force SBT to reload changes: Open SBT toolwindow (on the right side of IDE) and press refresh button.

If you use auto-import feature you need to save your file to force auto-refresh.

IF plugin gets 'stuck' it helps to invalidate cache (under file menu) and restart intellij.

As of 7 Dec, 2013, the issue is solved. You need to update the Scala plugin in IntelliJ IDEA (this applies to both community and ultimate editions).

This is the link to the issue opened on JetBrains developer community web site: http://devnet.jetbrains.com/thread/451395