I had a positive PPD test and my chest xray was clean so last year I was treated for 9 months with INH. Do I need repeat chest xrays every year to follow?

Not unless you have symptoms.  A chest xray is only indicated prior to initiation of INH to rule out active disease. Asymptomatic patients who have been treated with a full 9 month course of INH are not indicated for a repeat chest xray even if the PPD is positive.