It won't and shouldn't, since that would mean that your build isn't reproducible. Instead, you need to tell SBT about your dependencies explicitly. If it's available on Maven, add the dependency to your
build.sbt like this:
libraryDependencies += "group" %% "artifact" % "version" // if it's written in Scala
libraryDependencies += "group" % "artifact" % "version" // if it's written in Java
For libraries that aren't available on Maven, such as QT Jambi, create a folder called
lib in your project folder and put the jars there, and SBT will add them to its classpath.