If you are working in a QliKView Server environment, the server has this setting by default, that you may want to modify (number of max symbols in a chart). Go to the QlikView Enterprise Management Console, System, Performance, and change that setting.
In the document part, go to Settings menu, User Preferences, Objects tab, and modify this value "Max Symbols on Charts". Save and reopen the document.
Anyway, note that the higher the limit is, the longer the chart will take to render.
That should do.
Hope that helps.