New PERM application with the same employer

[anilsubash]

Hello everybody, 

I was offered a new position in sales within my company who filed for my green card in 2012. Currently I'm working as an Engineer. Though there is some overlap in responsibilities between the two positions, my HR and immigration team informed me that I need to apply for a New PERM and I-140. Does any of you have any experience with this,where they had to apply for a New PERM within the same company? Also, can you respond to the below questions. 

1. Can I use the experience from the company in my application
2. If I can?t how can I justify the fit for this job (having an engineering degree but supporting sales)
3. If the PERM gets denied, can I get back on the old PERM?

I highly appreciate any feedback on this. 
Thanks