We used an auto renewals in our contracts so that it just continues after the term for another term, and we also were explicit with pricing (ie year 1 pricing was discounted, but the base price was listed. The renewal was for the base price so revenue kicked up)
if you have a MSA, then you could add another SOW to it, that looks basically the same (1 page with the specifics). I'd add an auto renewal to the msa for future customers though