How long does a landlord have to make repairs he charged me for with my security deposit?

$1300 security deposit was given at time of rental. When I moved out, I knew the front door needed replaced due to damage. My landlord returned $300 of the $1300 with an invoice from a contractor showing the REPLACEMENT cost of the door ($900). However, I drove by the old rental yesterday, 3 months later and the door has NOT be replaced. How long does he have to replace the door before I can hire an attorney and demand my money back for something he did not do? I live in PA.