What is the condition of your kill line in the centre of your bridle cord? If it is getting a little furry then it is degrading. You might like it more because, unlike a new one, it will stay cocked longer where the parts of the packing process can cause it to un-cock as new lines slides through the bridle more easily.
What is the worst that can happen if a kill line fails? You end up landing with an inflated pilot chute. Most of the time this will be no problem. Then again as it will be adding drag to your canopy, it will slow it down and reduce performance. Performance you may need one day in a tight situation.
Overall, I would suggest that if there is any doubt, you should replace the kill line. Also it is a lot easier to replace the line before it breaks than afterwards.
The kit comes with sufficient line for most bridle cords around, a finger trapping tool and detailed instructions for the fitting of the line and adjusting it to the correct length. No sewing is involved.
Price $20 plus postage