If you can, get a Police report in respect of the lost blue book/RP card.
Re-enter on an eVisa and go to the Polis to firstly report the loss of the blue book/RP card and secondly apply for a new one.
As usual in Turkey, it depends on the weather or whether the person you speak to got his rice crispies that morning what happens next. You *may* get away with buying a new blue book/RP Card, you *may* have to pay a fee equivalent to half the unexpired portion of your residence permit or you *may* have to simply apply again. Those were the options under the old system administered by the Polis Yabancılar Şubesi and I've seen all three applied for a lost blue book.
Under the new system there may well be a provision for replacement - it'd be good if you could report back what happens when you go to the Polis, for the benefit of anyone else in the same situation.
JF