Not that long ago I redosed with AL-LAD and it certainly worked, but yea I had to take more. I also did it with LSD in the past, but it doesn't always work so effectively. Prolonging effects is much more likely and you won't really get another true peak - instead I'd say that the effects can change a little bit but it is very hard to explain in what way... I guess it can still be a deep mindset and body high, and can feel 'lucid' or stimulating, with the visuals and most of the truly interesting peak effects not really being revisited that much.
Whether it is worth it is very debatable, but 'pointless' is different than 'waste'.
If you don't have a whole lot of acid, and plenty of occasions to come... I'd just focus on appreciating the trip as it is, and leaving it at that. But if it is a really special get-together with friends tripping, with people being interested in pulling an all nighter with a nice atmosphere then yeah IMO its an option. Slightly similar to comparing smoking weed when you are not used to it at all (anymore), which feels intense and special - and smoking weed after you've been at it for a while - which keeps you high, and is nice - but different, and at some point just more of the same. It works, and you need more, but definitely not always worth to keep up.