Could someone clarify this query.

I use thick cream for icing (add icing sugar, other flavours or colors to it). Last time I accidently used the electric beater instead of just whisking the cream. It turned the thick cream to a runny consistency. I tried to add more icing sugar but then it was getting too sweet , refridgerated it it thickened a little but not good enough for icing.
How do I save the cream if such a thing happens , can I add corn flour to it and turn it into icing?