You certainly can, and depending on its age, it may be close to ten by now. A regular addition will tell you well enough. Perhaps use just a bit shy of what you normally put in. No biggie if it's a touch high when you test, and you'll figure it out from there. Good luck!
Just for clarification to others who read this. Liquid chlorine, liquid shock and bleach are all chemically identical except for the percentage of chlorine. Bleach is usually 6%-8.25%, liquid chlorine is usually 10% and liquid shock is usually 12.5%. It varies by state.
To add more confusion to that bleach bought from janitorial supply companies may be anything from 1% - 12.5%, many places sell the 1% junk cheap, and it tends to keep janitorial staff from going through bleach so fast, or at least so many $$$$ of it.