My ten cents.
Although Kinmassive and Chad have pretty much covered it.
Alternate rep ranges as Kinmassive suggests and you could also vary this every second week (or fortnight). Eg. 6-8 and 12-15 week 1, then 4-6 and 8-12 the following week (or fortnight).
Ditch the pushdowns and curls for arms. Then you can add pull ups as a vertical pull exercise – supinated close grip will give the biceps a good workout. And as Chad suggests dips are probably better than push downs.