Remember that the HD44780 has memory way past the first 16 or 20 chars you are writing to.

use this gotoXY routine to specify the next line

#define line_two 0x40 // address for the second line


void lcd_gotoxy(U8 x,U8 y) {
U8 lcdaddress;

if(y!=1)
lcdaddress=line_two;
else
lcdaddress=0;
lcdaddress+=x-1;
lcd_send_byte(0,0x80|lcdaddress);

}