conditional formatting updated by vba

hi
can you update conditional formatting in vba,sheet4 has conditional formatting highlighting rows using a textbox,if i add another say 10 rows it only looks up the original settings,have tried to increase number of rows but does not work or i can not get it to work,would like it to after i enter new data to extend its search and when entering a st number look through all sheet4,is this possible,as usual any help would be good
thanks
cheers colin