knotless tapered leader???

[sushi]

hello .. just want to ask ... when you use a knotless tapered leader if i purchase like a 9 ft 5x and use it on a fishing trip ... lets say i lost a couple of flies etc ... and keep on tying a new one whinch will make the leader shorter and shorter... when will i need to replace it??? or is it okay to add a tippet the one you buy on rolls???? how do you guys set up your leader and tippet anyway??? please let me know the best way to do this.... thank you...