It's rare to wear out quality track gear. I find if I ever NEEDED to replace something it was because it physically broke. Wanting to replace something is up to you and will happen soon enough. Get yourself a good buy on something nice and basic with true track geometry. That will get you 90% of the way to being an experience and serious track racer. It will be 2-3 years before you'll really know what you want and what you want to spend on a new bike.
I find the best way to approach it is to think that you can have two bikes. One provided to you free of charge, the other you have to purchase. "What bike could I have if money were no consideration? OK, now what bike WILL I BUY TO BE MY BACK UP BIKE?" Except you don't get the freebie. You just get to dream about it.