Sorry jpeast.
The Valuation of the Property is neither here nor there, if you have agreed a price with the vendor below this figure.
In this case, your Bank, if they are giving 92% Mortgages (I think only AIB and EBS to FTB's at the moment) will base the loan offer on 92% of what you have agreed to pay for the property,as long as this does not breach the 92% ceiling.
You will never again, under any circumstances, get a Mortgage on a property based on 92% of a Valuation, which brings the Mortgage to >100% of the price you are paying.
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EDIT: Sorry, I did not see the bit in your OP about this being for a top-up loan. Was the original Valuation for €190K, when was that?
Top Ups can have a lower overall LTV, as an existing customer, so the 92% would be extremely difficult.
There would also be the situation of your Mortgage Protection Policy, if you have Health issues, you must ensure that the Policy is for enough to clear the Full mortgage, including any second Mortgage (Top-Up). Have you considered this?