Battery Acid Recharge

[Colonel]

I have a six year old ford script repro battery that is marginal in starting the car. I have added water numerous times over the years. My hydrometer indicates the battery acid in each cell is very dilute and in the red zone. Can I add fresh battery acid to the cells and recharge? Thoughts..... Don't want to give up on the battery if possible. Don't want to have a safety problem either!