Increasing sensitivity of IR Receiver

I purchased a surplus remote repeater (turns Infa-red remote signals into rf, and broadcasts it to a receiver) that works rather well, but the IR receivers capability to receive is raher lethargic. Unless the remote control is quite close to the IR receiver it doesnt work...move a foot away, and it doesnt receive it at all. Is there a simple preamp circuit that I can place in between the detector and the transmitter circuit.
I have tried replacing the IR photodiode with one that is supposidly more sensitive, with limited success.
Thanks in advance

If it's not working beyond 1ft range there is likely something wrong with the receiver, is the repeater rated for the same frequency as your remote? That would explain the decreased range.