1.69 update broke something for me, I think ... lcd not working (HD44780)

First thing I would try is:

var ow = new OneWire(B13);
var temp = require("DS18B20").connect(ow);
    
function onInit() {
    I2C1.setup({scl:B6, sda:B7});
    lcd = require("HD44780").connectI2C(I2C1);
        
    setInterval(showData, 5000);
}
function showData() {
 lcd.clear();
 lcd.setCursor(0,0);
 lcd.print("Current temperature:");
  
 // Get the temperature
 var t = temp.getTemp();
  
 // Round it to the nearest 0.1
 t = Math.round(t*10)/10;
  
 lcd.setCursor(0,1);
 lcd.print("Temp = " + t + " C");
}
onInit();

That way, we're not trying to talk to the display until after we've set up I2C.