Applying Page Layouts - Issue for existing pages

Hi,

We have developed our Intranet in O365. We have some page layouts created and accordingly pages are created. We have made use of the Content Editor Web-part, but now we want to replace it with a JS. We modified the layout and published the same. Our findings are - for the new pages the change is reflected for any new page created using that page layout. However for existing pages it is not reflected. Has someone faced this kind of issue earlier. Need help in this case.

Thanks,

Anand

Thanks and Regards, Anand R. Deshpande