Tilly
I'm afraid we can't give you an answer to this question, only you can make such a Decision but some information that might help.
Yes, you are correct a Tribunal panel cannot take into account any changes in your limitations since the Decision was made.
Before making a decision understand why you initial claim has failed, if you don't have a copy of the Assessor's Report, a PA4 for and assessment or a PA3 for a paper review, request one from the DWP.
With the above in mind, would the deterioration you mention make it more likely that you would receive an award on a new claim?
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
