I have had to do this in the past when my users wanted me to renumber based on a grouping (e.g. at each division on the report).
If you right click on a section (along the leftside of the report design area) and use the Section Expert it has an option called reset page number after.
Like almost all the options on the Section Expert, you may also use a formula to make this decision conditional (e.g. at only certain divisions reset the page numbering).

Best of luck - hope this helps!