General Brazilian
aumentar o otimismo / elevar o otimismo
Most common usage in Brazil
São Paulo
aumentar o otimismo / potencializar o otimismo
Business contexts often use more formal terminology
Rio de Janeiro
elevar o otimismo / animar
Informal usage may include 'animar' (to cheer up)
Portugal
reforçar o otimismo / aumentar o optimismo
Portuguese spelling uses 'optimismo'; 'reforçar' is also common