That's pretty comical actually, but *****. At least you could just stop here and slide the spring back in.
Actually, what lift are you running? Personally I would just recommend some new rear springs. Such as the skyjackers or OME. I know its not right to have to buy new ones already, but it will probably be the quickest and easiest fix. I think the skyjackers are about 140 and the OME are 120. Limiting straps would work but they limit flex and would be a pain to fab up.
Looks like the lift manufactor used too short of a spring. Most of the lift was achieved with just increasing the spring rate not increasing the lenght of the spring. Get longer springs so they stay seated.
Just curious on what shocks your are running also. Dosen't look like they give more flex than the Rancho RSX17004 and those keep my OME coils nice and snug with tons of flex. So it seems as if the spring is just too short.