This looks OK on your demo, but if you re-enable animations this redraws the animations rather than smoothly updating.
This works - I don't even need to set the XValue Member to "X" - setting the YValue Members is sufficient for my needs.
To update your charts using AJAX requires you to understand that the page you're requesting via AJAX doesn't generate the chart. Another HTML page (eg the one you're currently reading) takes that data and uses it to generate the chart.
The sequence of events is: The RGraph AJAX functions that can be used to make the requests are part of the RGraph common library and you can use them like this.
This way, all animations are always from 0 to value which looks strange.