The phrase "to add some freshness" means to include something new or different in order to make something more interesting or exciting.
Sentences with «to add some freshness»
I like to add a little fresh lime juice to mine for added freshness. (fooddonelight.com)
Ginger adds a freshness of flavour, and along with miso, it helps to reduce stored environmental toxins like radiation, pesticides, cigarette smoke and air pollution. (eluxemagazine.com)
You barely taste the lemon, it just adds a freshness and nice smell to the situation. (hiddenponies.com)