You can change the subject when you reply (as I just did).
As far as I can tell, there's no support for using part of the found pattern in the replace string in the layout search and replace (it's not covered in the documentation, and the attempts I made using regular expression syntax didn't work either).
But a simple bit of SKILL code can do this (I'm assuming it's the labels you want to change, given your previous post):
procedure(CCFchangeLabelPattern(fromExpr toExpr @optional (cvId geGetEditCellView()))
when(shape~>objType=="label" && rexExecute(shape~>theLabel)
shape~>theLabel=rexSubstitute(toExpr) || shape~>theLabel
What the \\(...\\) parts are doing are recording that part of the regular expression for later substitution by the rexSubstitute - and then \\1 means the first bracketed part, and \\2 means the second bracketed part, etc.
If you're talking about altering the actual net objects in the database (e.g. because you've been using layout XL), then that's a bit more complicated - but I think you may be asking about altering labels.