save (something) up        
phrasal verb with save verb uk/seɪv/ us/seɪv/
A2 储蓄,存(钱)
to keep money so that you can buy something with it in the future
  It took me months to save up enough money to go travelling. 我用了几个月的时间才攒够了钱去旅游。 
 She's saving up for a new bike. 她正在存钱,想买一辆新自行车。