What I do is to use 2 buffers and I use sprintf for concatenating the strings, super flexible
char buffer [20];
char floatbuffer[10];
...
dtostrf(analogRead(A0)* (5.0 / 1023.0), 4, 2, floatbuffer);
// You can insert the float string anywere you wish here inside the final string
sprintf (buffer, "%s%s", "A0=",floatbuffer);
lcd.setCursor(0, 0);
lcd.print(buffer);