Renewing AST

Other

Hi there,

I have an excellent tenant who's 6 month AST is due to expire 28th Feb 2014.

She has advised that she would love to stay for a further 6 months.

She's in full time employment, always pays on time and has looked after the property during her stay.

My question is should I just keep her on a periodic tenancy or issue a new 6 months AST?

I also have a S21 in place (I always submit this at the beginning of a new AST just incase) so would this be invalid if I offer her a new AST?

Also would the deposit have to be newly registered if she signs a new AST agreement?

Thanks in advance.