how to update sketch?

Dear all

In my part file, there is sketch feature name "sketch 1"

If I have modified the skecth, that is to say I modified the some demention in this skecth.

I want to update this sketch, and I don't want to use "modeldoc2.editrebuilt3" I only want to rebuilt "sketch" ,not rebuilt "modeldoc2"

How can I do

thanks for andvance!

zhengjun Yuan

SolidworksApi macros