I've two FS kites that I've spliced a new loop in...so far, so good
I'm guessing you wore out the bit just above the CL? You can splice a line into a line and then add a loop on the end, so long as you keep the extra thickness below the stopper block at the end of the trim strap.
You can use the worn line as part of the tail bury, so you'll have a really long bury--it'll be super effective
The trick is getting the lengths right. And for OCD I like to try to hide where the splice end and the loop end finish inside the QR body...
So, basic idea is:
Cut the safety ring loop off just above the eye splice.
Poke a hole for the splice at the bottom of the trim strap (so the bar won't rub on the splice entry points).
Splice in the new FLS line (it's just front line, I think) and finish the tail near the stopper block.
Splice in the old FLS line.
Make a MacDonald Brummel and eye loop for the safety ring.
IIRC you'll loose about 7-10mm of length per 100mm of bury, but it doesn't matter too much. Long bury is strong, and you'll be doing 100x easy.