If you want to put it in EEPROM, then it will have to be done by the sketch. You can't use a separate sketch because it would put the wrong file name.
If you have to put it in EEPROM from the sketch, then you'll have to have the string constant in the sketch. And it will use all the same memory that it did when you weren't putting it in EEPROM. So there's nothing to gain there.
Looks like it is time to learn PROGMEM. "I don't understand it" is a bullshit statement. Nobody can help you from that. Talk about what exactly you didn't understand or what part confused you and maybe someone could help.