slave reset in spi interface

hello there! i am communicating two msp430g2553 using two nrf24lo+. when i transmit 'a', receiver gets 'a'. then if i transmit 'b'. receiver does not get 'b'. if i push both reset switch. then slave receives 'b'. can you tell me how to reset using software. i am using this routine for spi

UCB0CTL0 |= UCMST+UCSYNC+UCCKPH+UCMSB; // 3-pin, 8-bit SPI master

// Initialize SPI interface
// master mode, data valid on rising edge, msb first(Because NRF24L01
//wants MSB First)
//UCB1CTL0 = UCCKPH + UCMST + UCMSB + UCSYNC;

UCB0CTL0 |= UCCKPH + UCMSB + UCMST + UCSYNC;
UCB0CTL1 |= UCSSEL_2; // SMCLK

// (4)
UCB0CTL1 &= ~UCSWRST;