After joining some Lat/Long values to a non spatial table that is hosted in ArcGIS Online, there is no way to "Display XY Data" in ArcGIS Online.
In ArcGIS Desktop, this is as simple as right clicking and going through the prompts, however, in ArcGIS Online you must export the data and either then publish it or upload it once again.
This functionality would increase the user experience when working with tables in ArcGIS Online
