I thought the arduino is constantly monitoring the analog inputs.
That's up to how you write the program, but yes I think we're on the same page, maybe just consecutive paragraphs 
I'd take say 5 readings over 5 seconds, ditch the highest and lowest then average the other 3 and use that value as your current ride height. Then make an adjustment only if that value is sufficiently different from the value used last time you adjusted.
Rob