Only skimmed through the datasheet, but as usual:
You can simply shut down the receiver for as long as you're not using it. Then, wake it up every e.g. 0.5 s, listen for a couple milliseconds, see whether there's a preamble going on, and else go back to sleep.
It requires, however, that the transmitter sends a preamble for 0.5s. That shifts the power demand from the receiver to the transmitter.
That happens to be exactly the thing that the emergency pagers for firemen do.
I have an answer where I explained why receiving needs much energy; there's really no way around it. You can make your receiver less hungry by turning it off and on, but that requires a fast "turn on" time.
Also, your receiver should use as little watt per (bit per second) as possible. Your 470R seems to be pretty terrible at that – 2.5 mA for 1 kbit/s, where other receivers (example, see page 35, 36) do much more data with only a little more power. The quicker your reception is finished, the more you can turn off the receiver again, the less energy you used.
By the way, this is really a very basic receiver. You'll definitely have to add error correction, unless you can live with the 1% bit errors that the datasheet says all measurements were made with. And you usually can't. So, there's a microcontroller somewhere that takes the data coming out of your receiver, and decoding them, correcting errors on the way. You'll have to factor in the extra bits you need to transmit to be able to correct errors, and also the computational effort to correct the errors at the receiver, into your power design.