In '92 the Llandudno Heritage Trust, among others, commissioned a report into this. The report found the same issues as currently: the beach needs raising with several hundred of thousands of tons of sand. Of course, because of the cost, not a lot was done.
The cost will be at least £20m - possibly more - but needs to be funded by central government. If the PM was telling the truth, we'll have wads of cash after Brexit, and the PM wouldn't lie, would he?