Hi and as a friend would say "Welcome to the Asylum!"
The air bags will need to be replaced if it is the bags themselves that are leaking. It could also be a leaky air line or fitting where they travel to or attach to the bags. The best way that I know of to determine this is to mix some water with dishwashing liquid in a spray bottle, crawl underneath with safety glasses on (that spray goes everywhere with a penchant for the face and eyes), and spray spray spray everywhere you can find. Put a good amount on until it drips, and any leaks will be revealed by bubbles. If it's the bag, then you will see bubbles there. The leaks are often accompanied by a sizzling sound.
If you can't find any bubbles and you have sprayed down every line, hose, joint, and fitting .... then the bags themselves are likely to blame.
I couldn't see what year your Aspect is, so hard to say about longevity. Some seem to dry rot more quickly than others, and some last the life of the rig. That said, I've never heard of patching them or anyone who offers to patch.
Here is a link to replacement airbags for the Ford E450 chassis. The airbags are the same across a wide number of years. I have no affiliation with SDTruckSprings, but have purchased from them before and this will at least give you a ball-park figure or starting point for the cost of repair materials, excluding labor, should the bags require replacement. Labor and per-hour rates vary widely across the US; I've seen everything from 275.00 per hour to 100.00 per hour or less. You'd do well to contact a shop that does truck work and get an estimate. No need for an RV-specific shop but no reason not to go to a reliable RV repair either; the air bags are part of the Ford truck chassis underneath the motorhome and should be serviceable by any truck repair shop.
If it's just a fitting (and they do leak....ask how I know) it's a matter of finding the proper part number from either Ford or Winnebago, and replacing. Most of them screw/unscrew rather straightforward. Repairs are usually much easier than locating the leaks, which can be maddening.
Best of luck....