Old ready mix patching plaster

Hi,



I have half a gallon of ACE ready mix patching plaster that is about 2 years old and I need to use some now for a small repair job. But it has dried and become slightly hard. I can still mix it.



Can I add water to it and still use it? Or, wait until I can go and buy a new one?



Thank you.

Old ready mix patching plaster