RGB LED STRIP programming question

Other Hardware LEDs and Multiplexing
9

sorry for the poor description.
so right now, when the button is pressed, an led goes fading down the strip. i have a max/msp patch constantly feeding the arduino a value for the led. when the button is pressed, it only shoots one of these random values down the strip. i want it so that when the led goes fading down the strip, it keeps changing with the live values it is receiving via max/msp, instead of just one received value.
hope that makes some sense.
heres my code-

#include <FastSPI_LED.h>

#define NUM_LEDS 288

struct CRGB { 
  unsigned char r; 
  unsigned char g; 
  unsigned char b; 
};

struct CRGB *leds;

long RAND;

#define PIN 4

void setup() {
  Serial.begin(115200);
  pinMode(5, INPUT);
  pinMode(0, INPUT);
  FastSPI_LED.setLeds(NUM_LEDS);
  FastSPI_LED.setChipset(CFastSPI_LED::SPI_WS2801);
  FastSPI_LED.setDataRate(3);
  //FastSPI_LED.setChipset(CFastSPI_LED::SPI_LPD6803);
  //FastSPI_LED.setChipset(CFastSPI_LED::SPI_HL1606);
  //FastSPI_LED.setChipset(CFastSPI_LED::SPI_595);
  //FastSPI_LED.setChipset(CFastSPI_LED::SPI_WS2801);

  FastSPI_LED.setPin(PIN);

  FastSPI_LED.init();
  FastSPI_LED.start();

  leds = (struct CRGB*)FastSPI_LED.getRGBData(); 
  memset(leds, 0, NUM_LEDS * 3);
}

void loop() { 
  
  int button = analogRead(5);
  if (Serial.available()>=1) {
      RAND=Serial.read(); 
  
  if(button > 1000) {
     
      leds[0].r = RAND;
      leds[0].g = RAND;
      leds[0].b = RAND;
     
      }
  

  
  // Move all the lights down one step
  for(int i = NUM_LEDS-1; i > 0; i-- ) {
      leds[i].r = leds[i-1].r;
      leds[i].g = leds[i-1].g;
      leds[i].b = leds[i-1].b;
      
      }

      leds[0].r /= 2;
      leds[0].g /= 2;
      leds[0].b /= 2;  
      
  }

      FastSPI_LED.show();
    delay(30);
}