Replicate is a keyword ability.
It is an ability which can apply to both instants and sorceries. It is the ability to produce one or more copies of that spell, each with its own target. Each copy is its own standalone spell, so even if the spell which corresponds with the physical card is countered, each copy still resolves independently.
- 702.76a Reinforce is an activated ability that functions only while the card with reinforce is in a player’s hand. “Reinforce N—[cost]” means “[Cost], Discard this card: Put N +1/+1 counters on target creature.”
- 702.76b Although the reinforce ability can be activated only if the card is in a player’s hand, it continues to exist while the object is on the battlefield and in all other zones. Therefore objects with reinforce will be affected by effects that depend on objects having one or more activated abilities.