How to fix a failed slip test?
To fix a floor that failed a slip test, work out why it failed, then deep clean, apply an anti-slip treatment, add a slip-resistant coating, or replace the surface, and retest after the works.
A deep clean suits contamination or residue. An anti-slip treatment such as a chemical etch or surface treatment suits tile and stone that can stay. A slip-resistant coating suits a floor that needs a new wearing face. Replacement is the last resort.