fnDraw after external table modification overwrites external changes

I'm in a bit of a hacky situation where I'm using DataTables to manage a table that is also controlled by some other JS. The external JS occasionally changes the values in the table, but when DataTables redraws, those external changes are lost.

I may be able to workaround this by never redrawing the table, but I'd like to maintain the integrity of the DataTables object. What do I need to do to tell DataTables that some cells have been changed so that redraw uses the new value?

Thanks~