ON/OFF safe implementation
If this is a battery-powered device then you're probably best putting a hard power switch between the 9V source and the rail to prevent leakage. This isn't an absolute fix - the battery will still have self-discharge and it prevents any standby operation for your uC. Ultimately it does depend on your application. 

If you need standby operation then you either have to let the 9V source remain connected and active while the uC is in low power mode, or if your power usage is low enough you can put a huge capacitor on the power lines for the uC as a pseudo-battery backup. You'll probably want a diode to prevent the capacitor from discharging into the rest of the 5V rail in that situation. It also depends on what components the uC will need to have access to while in standby - can the IR sensor wake it up? It would need to be powered.

Also, it seems somewhat dangerous to include lightning in your circuit :)