Is this ok to change my work out?

Since December I have been doing heavy weight lifting four sets 6-8 reps three times a week. I bulked up a good amount .I switched my work out to 5 sets with 12 reps with lighter weight to get definition. I think it would be good to help shock the body so I can get further results . Instill doing the same exercises though just lighter weight. Would this be ok?