Can Damaged Plants Survive & Become Healthy Once Again?

[totally tropical]

If I have made poor decisions regarding the keeping of my plants, will they then re-grow when conditions are right?

For instance, I have a large amazon sword which was kept in the wrong conditions and it is now littered with small holes on all leaves (some decimated), now that I have gained a little knowledge on keeping these plants should I just throw out or will it eventually pull round and form new leaves?

Thank you.

 

[tropic_john]

Most plant keepers cut off the most unhealthiest leaves about 1/2 an inch near the stem and keep the most healthiest. They normally grow back

 

[Nick16]

Most plant keepers cut off the most unhealthiest leaves about 1/2 an inch near the stem and keep the most healthiest. They normally grow back

actually the trick with amazon swords is not to cut the leaf, but to pull it away at the part at the bottom (think its called rosette) by pulling it away it is much better for the plant, leave a couple of healthy leaves on there and let it grow back.
holes in leaves are a sure sign of a shortage of ferts in the water,

Ferts
Co2
and a nutritious substrate are a sure way to improve all plant life in your tank.