well i have the same issues with my network.
my last operation was to replace the repeaters with big 9dbi antenna and nano io shield which give the nrf direct power from the 12v socket (through 3.3 reg' of course).
and still losing contact from time to time.
**next phases **
1 wrapping the tinfoil shield discussed here
2 adding relay to software reset the arduino (gnd and rst connected to relay - like arduino pressing its own reset button)
* 3 replacing nrf with rfm69-433mhz - some say theyre better although require some soldering wires and logic converters (i'm waiting for my order from ebay to arrive.)
about this library fail attempts modification - i didnt find something, but maybe MySensor.h has something in it - but i need some proffesional eyes here,
BTW my setup is domoticz on Rpi, S-GW, E-GW, most nodes with nano-io-shiedl + nrf-pa-lna, library v1.5
