What your loop is doing is telling Tk that you want to change the configuration of your widgets, but never giving it a chance actually to do it!

You should call $radiovar->idletasks (or perhaps $radiovar->update) somewhere in your foreach loop (say after update_go_array, if you've finished your reconfiguration by then). See the Tk::Widget manpage for details of these methods. This will give Tk a chance to display the updates you've made.

On a side note, why are you saying &subroutine() instead of subroutine()?