to gradually get more points, profits, etc.

He has racked up 450 points in three months. 3个月内，他已经累积了450分。

Astronomical profits/losses were racked up by airlines last year. 去年各航空公司累计盈利／亏损达到了天文数字。

to increase something such as a rent or price, especially by an amount that is considered to be too much

Our landlord racked up the rent by 15 percent this year. 我们的房东今年把房租猛涨了15%。