If you create the text, than you are responsible for the wrapping. That the 'change attributes' does the work that you should have done is a plus, not the way ;--) (think triggered by the possible change of the textstyle)
How are you creating the new content of the textnode currently ? Somewhere in the textparams there should be stored an information about the textwrapping lenght. So it's up to you to add additional line(s) to your textcode, if this length is shorter than the text you try to create. Maybe you will even need to concat the whole text before tearing it in pieces of the correct (maximum) length.