Make wingspan bigger
The best way to get your plane to fly on for a long distance is for you to increase the surface area of the wings on the plane.
The bigger the surface area, the higher the chances that the plane will fly longer. This is because it will be able to resist more wind with its now bigger wingspan, helping it stay afloat and in the air for much longer then you would have hoped for.
However, you need to remember that fast launching this sort of plane will cause it to break down almost instantaneously.
Add weight and fold wings
Another tip to get your plane to fly for a longer distance, and for it to help maintain its stability is to add weight to the nose.
Adding weight to the nose can be done via the usage of a paper clip, tape or some extra weight that you can place over there. This will help the plane stay on course, and not be subject to wind direction and pressure changes.
Now folding the wings upwards may seem like it is not a very smart thing to do, but it will help your plane out quite a bit, as opposed to wings that are folded downwards. This is because it will help the plane float on, and prevent it from tipping backwards.
The last thing you need to do, is to work on your paper plane launch. Not being able to release the plane properly will end up taking a lot away from your flight, and it will also never let your plane fly to its maximum potential. This is why practicing to launch the plane properly is very important.