Reducing spice in sauce
There is no robust way to do this in the general case, other than to create  second batch with no additional hot peppers (or a reduced quantity), and combine them.  Of course, then you will have twice as much product.

In some cases, adding a masking agent like sour cream or cheese, which tame the effect of the spiciness may help, but those methods would be very odd with a Chinese dish.

Depending on the degree to which you have over-spiced your sauce, simply using it more sparingly may help.   Traditionally, Chinese food is not swimming in sauce in any case.