either transplant to a bigger pot or remove the rootball then re-fill the pot like a normal transplant. i dont see very much point in putting the soil on top to fill it, you want your roots to go downward into new soil, you should of completely filled that pot from the start. they are not looking very good for 5 weeks(no offense). have you switched to 12/12? cuz that plant looks like its got alot more vegging to do before it shows preflowers.