hi, im not 100% sure which model you have (it could be the drobo-s but sales or dashboard might be able to help confirm the model name), but essentially if all lights are green, then there are several migration paths that you can follow, for example as mentioned on this page:
if you do have a drobo-s, then it looks like a 5D or 5Dt could be the way to go.
one thing to bear in mind though, is that if the cause of the problem, is the current, older drobo model (such as connections to the backplane where the drives meet the drobo), then the migration could very well improve and fix that…
however, if the drives are essentially on their last legs, then it might be better to actually get another drobo that you want to use (like a das model with usb or thunderbolt if you prefer those instead of network cable models), but to actually also get enough new drives (ideally) and to simply copy your data while it is accessible, onto the new drobo (and onto the new drobos new/good drives)… otherwise, the problem might follow you around.
while it would cost more to get new drives, i think it would be better then trying to use your existing drobo to upgrade (and ultimately swap out and replace each old, potentially bad drive, with a good drive, 1 by 1), because doing that would also cause rebuilds and put more strain on the drives, which they might not be able to tolerate depending on their condition.)
if you did get a new model, you can get some support too (or if you just wanted to, you could also raise a pay-per-incident ticket with the support team where they might be able to tell from logs analysis, if there were any particular drive(s) that were causing your current problem, but in the long run it might be good to get another model anyway)