Welcome to the Org & the Main Hall, Irishfusilier!

Although I myself am not a modder (and therefore couldn't tell you how), I know that it's relatively easy to change the end date of 1453.

I have little doubt that one of our fellow patrons here will stop by and tell you how you can mod the end date. In the meantime, however, I recommend you check out the Repository--odds are very good you'll find the answer there.