SPBRG is the USART register. so just writing to it change the baudrate.

SPBRG=x
SPBRG=y
'
'
'
and so on

AND you could also skip all DEFINEs, just write to the according register... as the PICMultiCalc .

Code:
RCSTA = $90 ' Enable serial port & continuous receive
TXSTA = $24 ' Enable transmit, BRGH = 1
SPBRG = 129 ' 9600 Baud @ 0.16%