If they're leaking all the way along the seam there isn't much you can do. There's a guy over here who does wetsuit style repairs on waders, but that's only a temporary fix and probably not worth the investment. Similarly, you're going to get through a metric ****-ton of Aquaseal or similar if you have to try and re-seal full seams. It sounds like you'd be throwing good money after bad to be honest.
What you could do perhaps is use them for summer work and where wading deep isn't required, in conjuction with some quick drying trouser/base layer etc. You'd probably have to dry them inside out after each use (which we should all be doing anyway in theory). Sometimes cleaning them can help restore the water repellancy/breathability but if they're leaking down the seams that's probably not going to help.