It is a question that you really need to ask your IP, as there is no consistent answer. If your IP uses the IVA protocol, as I do in my practice, the property will need to be revalued in month 54 and equity raised subject to a maximum loan to value level of 85%. There is a £5,000 deminimis level, but a number of creditors are now seeking to remove this by way of specific modification - which goes against the spirit of the protocol and is currently under review.
If your IP does not use the IVA protocol, the above requirements are likely to be modified into the proposal in any case.
Using your own figures of £150k and £134k - 85% of £150k is £127k - so you would not need to raise anything - however your property is likely to appreciate over the next four and a half years.
Regards, Melanie Giles, Insolvency Practitioner