85%LTV basically means that the loan cannot exceed 85% of the value. Check your agreement, but there are usually other limits ... the remortgage cannot add more than 50% of your IVA payment to the mortgage payment and you should not have to extend the term of the current mortgage.. So, if your house was valued at, say, £160,000 you need to try to remortgage up to 160,000 x 85% = 136,000 (subject to the other limits mentioned).
Most people try with the current lender as well as make online applications (they generally don't get further than admitting they have an IVA!). Many IP's accept a screen print of the "Go Away!" screen as a rejection letter ... but some don't.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014