I can't work out how the 准备 fits in, but ignoring that, it seems to say:

the value of these assets can be marked back up if there is evidence to suggest that their value has recovered, but they can't be marked up to more than their current balance sheet value minus the appropriate amortisation.

So, for example, the assets are now on the balance sheet at 100.
We think they're actually only worth 50, so they have to be marked down. If next year their market value goes back up, you can mark them up again in your books, but only up to a maximum of 90 (100 minus 10% depreciation/amortisation).

My understanding:

"On the date of the Balance Sheet, for investments that are held until maturity, if there is material evidence to indicate that losses have happened, the losses (write-down) should be determined as the differences between their book values and present values of their forecasted future cash flows; if after loss provisions have been charged, there is evidence to indicate that the investments have recovered their values, then the losses (write-down) determined earlier can be added back into the profit/loss of the current period. However the book value of the add-back shall not exceed the amortized cost of the said financial assets on the add-back date when they were assumed to have no loss provision charges."

I think in here 减值损失 also means "write down", not just "loss".

Hope this helps.

…(该转回的账面价值)不超过假定不计提减值准备情况下该金融资产在转回日的摊余成本。

…Under the circumstances of no assumed devaluation provision, (the reversed book value) shall not exceed the amortized cost when the financial assets were reversed.