As someone who is in a university caving club and helping to run it, most of our new first time cavers will only come on one trip with us, after about a year we will be lucky to maintain 1 out of ten. The club advertises it's presence within the university and specifically organizes beginner trips and training to less sensitive caves.
But to most people caving is a pretty weird / extreme activity and they really join to just give it a try, which is all we can really ask anyway. Our club is set up predominantly to give students the opportunity to try caving out without having to buy a whole heap of gear or pay huge membership fees ($10 is our membership fees for new cavers). We usually have free beginners trips and after that we charge trips fees to cover wear on ropes, helmets, lights, etc. Beginners only need to bring batteries.
University clubs here in Canberra anyway are extremely important for getting new young cavers and act as a feeder for the caving clubs with older, less sport-caving oriented members.
A contentious issue with the ASF (Australian Spelio Foundation) was that university clubs could have lower membership fees. This is recognition that the university clubs did a large part of the recruiting for other caving clubs and the fact that we had a large amount of one off members of which it was unreasonable to ask full ASF membership fees because they were with the club for a single trip.
Another point is that with student members passing though the club every 3 years or so those members we do maintain will be moving on soon anyway. So the club heavily relies on old members still in Canberra to provide the experience necessary to run and organize the club and / or trips. It is probably useful for clubs / grottoes in the same area as university clubs to try and ensure that the university clubs get this stable expertise so that they can survive. Just imagine what would happen if every 3 years your grotto's leadership and most experienced members moved away, it decimates the clubs experienced members, who are few enough anyway.
So if your grotto is in the same area as a university club consider making some links with them and help form the experience base within the club.
end of my rant