Unless I'm missing the obvious again (https://bugs.kde.org/show_bug.cgi?id=336522) there is no way to make the height of the launcher window bigger. Currently for me, it is less than the height of my screen and does not hold all of my favorites, and so requires using the scrollbar and is less handy. It was resizeable in plasma 4 but if there is a way to resize it I cannot for the life of me find it. If there IS a way, it should be made more obvious.
*** This bug has been marked as a duplicate of bug 332512 ***