Resume redstone signal transfer as chunks load

Solution 1:

I'm not sure if this is still an issue, but I would suggest a series of clocks, each within the range of the previous, that would be enabled by your redstone line of choice being turned on, and disabled when it was off. These would have a redstone line traversing into the unloaded chunks, where it would trigger a piston pushing a redstone block into the circuit. Once activated by the redstone block, those lines would continue to be active and activate further clocks along the line.

Although this method will only work once the previously unloaded chunk is loaded, it should update the redstone afterwards, provided that it is powering a section of the redstone that overlaps with the previous powering.

Another suggestion is just to cave to the option of the nether portal chunk loader, shown here. It may not be low tech, but it works in most circumstances.