Ask Mr. Smarty Plants

The first thing we had to sort out was which fern is the "Japanese fern" you're referring to. When we searched on "Japanese fern", we got these websites:

Kemper Center for Home Gardening Athyrium niponicum var. "Pictum"

Perennial Plant Association Athyrium niponicum var. "Pictum"

Hardy Fern Library Osmunda Japonica

Pictures of Osmunda Japonica

Pictures of Athyrium niponicum

When we searched on "Japanese painted fern" we found another called Anthurium niponicum var. "Pictum" on this Gardening Made Easy site Japanese painted fern. And when we looked at our own native ferns, the genus is Osmunda, as in Osmunda cinnamomea (cinnamon fern). It would appear that the Anthurium niponicum is the accepted scientific name for the Japanese painted fern; that is, until they change it again.

The pictures, descriptions and care instructions on these all looked really similar, and we finally concluded that some committee somewhere, in its infinite wisdom, changed the Genus name from Athyrium to Osmunda, or vice versa.

So, having performed this exercise of trying to find out what we're talking about, we found no real reason for your ferns, whatever they are, to be feeling out of sorts. As best we can tell, you are doing everything right in caring for them, moist soil, compost and mulch, and so forth. We could find nowhere any indication of a normal lifespan for a fern, except that the Japanese ferns were slow-growing, and you would infer from that they were also long-lived. Frankly, we would give them another year to recover before we gave up on them. Read all the information in the websites we have linked you to, looking for pests and diseases, etc. It has been a very harsh, hot, dry Spring in Austin, so perhaps a little more shade and a little more water might help them perk up. And, being trimmed back at the appropriate season helps most plants regenerate. Trim your ferns back hard in the Fall when they begin to close up for the Winter, and hopefully, they will rise again.