I have have a hook and eye orbital sander. My problem is that the sanding disc come flying off after a few minutes. Is there anything I can do to increase the duration the discs are in place ?
Assuming you're using the correct adhesive system for the pad, there are two instances where this will happen:
1) Your pad is old and will no longer hook the loop, you'll have to replace the pad, generally about 15$ and you can easily do it yourself.
2) Your pad is incompatible with the sander you're using(rare if you're using the same system). It happens sometimes even with the same system sanders where the hooks on the sanding pad are agressive as are the loops on the disc, causing the loops to tear off the disc damaging the hooks on the pad. This may have happened in the past.
I have owned five different brands of sanders that use hook and loop attachment. Every sander, after four or five uses will no longer hold the paper. I purchased a new pad for the Porter Cable sander and again after four or five uses it will no longer hold the paper. The new pads cost about $10. That is too expensive. It is difficult to find a sander that doesn't use the hood and loop system. The solution in my opinion is to buy a replacement pad that utilizes adhesive pads.
Others have correctly identified that the backing plate with the hooks is a replaceable wear item on the sander.
What others haven't mentioned is that your technique with the tool can accelerate its wear. Let the sand paper do its job and also learn to recognize when it is worn out. Don't exert excessive pressure on the sander in an attempt to make the sand paper cut better. Pressing down hard does help wring out that last bit of life from a piece of paper but it also crushes the hooks on the backing plate. In other words, it causes premature failure of the backing plate.