The Grade I listed monument was designed by renowned architect Sir Edwin Lutyens, who also created the Cenotaph in Whitehall, London, and was officially unveiled by two war widows in July 1925.
The council said some cleaning and minor stonework repairs were carried out in September 2022.
However, due to the location and the porous nature of the stone, regular cleaning is needed, it added.
A council spokesperson said: “Restoration experts carrying out the works are using a gentle, eco-friendly cleaning method that uses high-temperature steam to clean surfaces without harsh chemicals.
“The works will ensure it looks its best for this year’s Remembrance Day commemorations, which will also mark 80 years since the end of WWII.”
The project has been funded through the council’s Capital Programme Fund.