Hi,
With SPI there's always one master and one or more slaves. The master is always responsible for generating the clock. In your case the PIC would be the master and the TRH031M would be the slave. Master/slave has nothing to do with the direction of the data, it can go from master to slave, from slave to master or both ways.

So, yes, of course you can send and receive data to/from the TRH031M without reprogramming it - it's already "programmed" to act as a slave.

/Henrik.