I don't think that with a reboiled absorber alone you can win back the LPG fraction in a off gas stream. I think you need also a compression step to first get the LPG fraction in liquid phase first. THen you can use a distillation column to separate various fractions.
To verify wether it is economical or not, you should determine how many piece of equipment you need, estimate their sizes, and finally the total installed cost. You of course also know the price of the LPG. if the difference is positive, then it is economical to win back the LPG is negative, it is not.