So, other than fixing the dram design, the solution is to refresh more frequently. A software fix might be a high priority background program that forces a full refresh at regular intervals (probably a big performance hit). If the CPU does its own dram control, there might be a register that affects refresh rate, or perhaps a microcode fix.
The problem is analog in nature, which suggests that optimized and very clean supply voltages, and very clean and precisely timed control signals might reduce or eliminate the problem.
In any case, this means that manufacturers need to fix their designs and test them more thoroughly.