when i practice my flight planning, i draw a route of my flight with a pencil on the actual chart. but because i constantly erase to draw a new route the chart becomes barely readable, and now need to buy a new one.

is there some trick so I don't have to draw on the actual chart and go buy a new one??

i even though about copying a chart on color printer, and have in with me (have one route on the cart, and alternative route on the copied pieces of paper)