PIP review and previously obtaind evidence

Could someone help me with some information. I was called for a review of PIP back in April 2018. my Award at that time was enhanced rate care and Mobility. Following the review and F2F assessment the enhanced rates were removed despite the expiry date in 2019. I have had a reconsideration and am in the process of appeal. My question at this stage to keep things simple is. Q Do the DWP/Atos have to consider all previous information obtained previously in a claim, or do they only consider what has been presented with the reconsideration form. ie; things harder, easier, same.

my point being full particulars of claim provided at start of claim and accepted, reviewed at F2F re-assessment previously and continued..

thanks for any help or advice from here.

Thank you Gordon.
Regarding further medical evidence. Are the DWP or ATOS under any duty to obtain further information from G p or Consultants involved in your treatment.p

Or is all the burden of proof with the individual claiming. Physical issues not to difficult to show. Mental issues Depression a different thing entirely.

Thanx Gordon. Sounds like a further up hill struggle to gain one's entitlement.