Look at the "Blink Without Delay" for an example of how to do scheduled things (like increasing and decreasing motor speed every 10 miliseconds) without putting in delays. Then you can do serial i/o at whatever interval you like while still making steady changes to the PWM output.
Note: analogRead() only works on the Analog Input pins, not the PWM Output pins. If you want to send the value you just sent to the PWM pin you should save that value:
if ('time to increase the motor speed)
if (time to send the speed value)