Needles get dull so quickly because the sharp points degrade quite quickly; within a couple of uses.
Re-using needles can do significant damage. It may not be obvious, or apparent to you at the moment - but there are a variety of reasons why needles are "single use". It's not only the damage blunt needles can do to veins over time, but also the potential for serious infection, because if you're not injecting with sterile works, you run the risk of introducing bacteria, viruses and other nasties into your bloodstream, bypassing the body's major defences.
Basically, re-using rigs increases the risk of serious harm as a result of IV administration of drugs.
We're not just giving you a hard time - the risks associated with reusing needles is one of the most avoidable types of drug/related harm.
Ideally you should use a clean syringe every time you puncture the skin - not just every hit.
You might have been fortunate enough to avoid harm related to IV drug use so far, but that's no guarantee your luck will continue. Using blunt points puts totally unnecessary stress on your veins, because it's not difficult to obtain needles online nowadays - they're cheap and can be bought anonymously, delivered to your door.
As for practical advice, i only have 2 suggestions.
1. As others have said, needles can be bought online
cheaply.
It's
your health we're talking about, but really - there is no reason to cut corners with something as (already) dangerous as IV drug use, when you can simply and cheaply obtain new, clean works.
2. If you can't buy clean needles online for some reason, you need to look at using a different ROA when you're in a pinch.
Plugging is the best option for a lot of people - it's a fast-acting, efficient way of taking most drugs, and can be done safely with a syringe that's been used hundreds of times - just remove the syringe.
You can get oral syringes - the sort most people recommend for plugging - from any pharmacy without any dramas.
Again, it's your choice and your health - but nobody here is going to give you tips on how to keep using a disposabe needle that has long passed its single use.
Not just because Bluelight is a harm reduction site, but because there is no practical advice to give on the matter besides "stop IVing until you get new rigs".
It's not because we want to lecture you, but because we want to give you the best possible information to stay safe.
while you wait for the package, learn to plug your drug 
