If you "peak" a battery, that means the charger will charge the pack to its maximum capacity. The charger will automatically shut off and discontinue charging the pack..
If it were my pack and charger, I would put it on the highest charge rate and let it cook. The charger will shut off when it's done charging.
Like BTB said, it sounds like you have a 1500mah pack. (mah= Miliamps/hour), this is the capacity of the pack. The higher the mah, the more it's capacity, therefore the longer the pack will last per charge.
A simple rule of thumb about charging...
By charging at 1 amp it will take approx 10% of the packs capacity to charge, in hours..
Example... You have a 1500mah pack, charging at 1 amp will take approx 15 hours to charge (because it's a 1500mah pack).. 2 amps will be 7.5 hours 3 amps will be 5 hours to charge and so on.. Make sense?
I wouldn't charge an old pack much harder/higher than 4-5 amps. Anything harder, it will just "false peak" the pack and could potentially burn up the pack.
After you have that all figured out, I can explain how to "Cycle" your pack to bring it back to life, but that is for another time... I don't want to overwhelm you anymore than I already have.

I have "Race" packs, that I found in the Garbage at the local track back in the 90's, that are still in use!!
Trip..