Your first step should be to request a copy of your assessor's report, then you'll know exactly what they've said and which items you need to challenge.
Do notify them that you want to take it to Mandatory Reconsideration and make sure you get that information to them within their time schedule. Always send things Post Office Tracked Next Day Delivery because then you have a record of your paperwork arriving on time. You can access the Timestamp and signature of person receiving it on the Royal Mail website.
Keep a copy of everything you send.
People will advise you to ask for letters from a consultant or GP to describe how your condition affects your daily living. Be aware that many medical professionals won't do this because they do not witness your daily life, therefore they cannot say exactly how your condition(s) affect you throughout your day and night.
Did you submit a diary to show how your symptoms affect your daily living?
Have you checked what you wrote on this claim-form against your previous claim-form to see if there are any discrepancies?
Since your last claim, have you had any other treatment which has affected your condition(s) and did you notify DWP?
I'm so sorry they have stopped your PIP, it could be a long fight to have it reinstated if it goes as far as Tribunal, but please don't give up.
Tribunals are independent and their members are aware of the DWP's tactics, you will get a fair hearing, but you must remember to present as much evidence as you can, factually and clearly.
CAB and Benefits and Work have fabulous guides for you to follow at each stage of the process. It's worth reading them and understanding that each specific task in the descriptors must be able to be done safely, repeatedly, to an acceptable standard and in a timely manner.
If you canot do that, you need to explain precisely why not in every instance.
I randomly googled this, there are many more sites with this info, I've not seen this site before so cannot recommend it.
www.mypipassessment.co.uk/updates/what-are-the-reliability-criteria-that-are-used-during-the-pip-consultation/