LCD Pushbuttons - switch?

Hi, I got this screen attached to my uno. The full code is at the bottom of the link https://arduino-info.wikispaces.com/LCD-Pushbuttons

I want to display a starting value of 25g on the screen and then when I:

  1. Push the up button - I want it to add 5g to the start value and display this (and then wait for new input)
  2. Push the down button - remove 5g (and wait for new input) So same solution as in 1.
  3. Push select - Move on in the code.

My question and the problem, can I somehow perform an action when a button is pressed and then stay in the switch? Or should I use a different approach.

switch (lcd_key)               // depending on which button was pushed, we perform an action
  {
  case btnRIGHT:
    {
      lcd.print("RIGHT "); 
      break;
    }
  case btnLEFT:
    {
      lcd.print("LEFT   ");
      break;
    }
  case btnUP:
    {
      lcd.print("UP    ");
      break;
    }
  case btnDOWN:
    {
      lcd.print("DOWN  ");
      break;
    }
  case btnSELECT:
    {
      lcd.print("SELECT");
      break;
    }
  case btnNONE:
    {
      lcd.print("NONE  ");
      break;
    }
  }/* --(end switch )-- */