“再投资于”常见的英语表达是 “reinvest in” 。例如：
The company decided to reinvest its profits in new research and development projects.（公司决定将其利润再投资于新的研发项目。）
After selling the property, he plans to reinvest the money in the stock market.（卖掉房产后，他打算将这笔钱再投资于股票市场 。）