What you need is for the bibliography template to accommodate dynamic changes linked to page numbers cited in an in-text citation. Unfortunately, Endnote is unable to accommodate what you are seeking to do.
It seems a bit usual to include pagination info in the bibliography entry when it is already cited in-text – why the need for duplicated info? Is this a style guideline requirement for publication? Although Endnote cannot accommodate your requested format a possible workaround is to create a custom field to accommodate pagination info to be inserted in the bibliography template. This will create a bibliography entry showing the pagination. However, this is a static fix (not dynamic) fix so it calls for manual adjustments each time the relevant bibliography entry needs to be modified.