Hi Mou,
Take a look at the MC13192 Reference Manual, SPI Register 0x12, PA_lvl. You have some control over the power level and drive level of the transmitter. You can see what the settings are on your current system and crank them up. Table 6-3 shows that you can get up to 4.1dBm, which may help. The default setting is for just under 0dBm.
Thanks,
Rick