Neste caso, "we must remain cognizant", a meu ver poderia ser traduzido por

"devemos estar cientes/devemos continuar cientes..."

http://www.websters-online-dictionary.org/definitions/cognizant?cx=partner-pub-0939450753529744%3Av0qd01-tdlq&cof=FORID%3A9&ie=UTF-8&q=cognizant&sa=Search#906

 
    
Part of Speech Definition   
Adjective 1. (sometimes followed by `of') having or showing knowledge or understanding or realization or perception.[Wordnet]
2. (usually followed by `of') having knowledge or understanding; "our youth are cognizant of the law"; "I am well aware of his limitations".[Wordnet]
3. Having cognizance or knowledge. (of).[Websters]
4. Being aware or awake. [Eve - graph theoretic]
5. Being wise or erudite. [Eve - graph theoretic]
6. Being competent, apt, capable or appropriate. [Eve - graph theoretic]
7. Being sensible, knowledgeable, intelligent or rational. [Eve - graph theoretic]
8. Being familiar or conversant. [Eve - graph theoretic]
9. Being expert or adept. [Eve - graph theoretic]
10. Adjective base of the adverb cognizantly.[Eve - graph theoretic]