Using FET as SPST switch to feed H bridge with boosted voltage
You could try this circuit







simulate this circuit &ndash; Schematic created using CircuitLab

Remove the two 4.7kOhm resistors, and connect the diodes to A2 and A3. When at least one is at 5V, then it means that you want one of the following conditions:


Forward (A3 high, A2 low)
reverse (A2 high, A3 low)
brake (A2 and A3 both high)


Then, the BA6208 must be powered. The two diodes + R1 form an OR gate, and therefore turn on Q1 if at least one of A2 or A3 is high. The collector goes to 0 V, then the PMOSFET turns on.

If both A2 and A3 are off, Q1 is off, its collector is pulled high to 9V and M1 is off too.

Still, I don't know if continuously applying-removing power to the BA6208 might damage it. A better solution would be the following:







simulate this circuit

Then, your program will enable/disable the power, by outputting A4 high/low. 
You should implement a software retriggerable monostable, that is:


Do I need to move forward/reverse or brake? Put A4 high and reset a timer.
Have some seconds elapsed since the last forward/reverse/brake operation? Turn off the power, by pulling low A4.


NOTE:
In each schematics M1 must be a 5-V logic level MOSFET.