Lashing Your Warp
I have cut off the project I planned for a warp I really like, and now I want to "play" with what is left. I recall seeing somewhere that, to make best use of a short warp, it is possible to run a "cord" through the tied ends and at the same time wrap the cord around the apron rod. Are you able to confirm this and, hopefully, advise me how to do so or point me in the right direction as to where I can find details of this method?
The method you are referring to for tying the warp onto the apron rod is usually called "lashing." You tie the ends of small groups of warp (to save the most warp, I'd make these very small, maybe a half inch of warp width) in overhand knots at their ends (the closer the knots are to the ends of the threads, the more warp you save). Then, you take a long smooth cord (about three times the warp width), tie one end to the apron rod on one side of the warp and then take the other end though the threads in the first bout just above the knot, back around the apron rod, through the threads in the next bout, back around the apron rod and continue until you have secured all the bouts to the rod. Then you tie the other end of the cord around the apron rod. Usually, you pull on the cord as you go so that there is about an inch length of cord between the rod and the knots. When you start weaving, your piece can begin fairly close to the knots and your only waste is the amount of warp taken up by making the knots.
When I first read your question, I thought you were talking about the other end of the warp. I thought you were wanting to save the part of the warp that you tied onto the back apron rod before you started beaming the warp. I wasn't sure saving that small amount of warp would be worth the effort of rolling the warp forward, keeping the tension even, and untying and then lashing the warp threads to the back apron rod. In rereading, I think you meant retying at the front. But if you do happily weave and weave and come to the point of seeing the back apron rod coming up over the back beam and you want just a few more inches, you can do the lashing process back there, too (provided you tied on there in the first place).