new planting alfalfa

Have two ac. alfalfa,planted aug. of ' 14 ...roundup ready seed. The stand is on the thin side. I am looking for options, i.e. replant alfalfa this fall or orchard grass etc. Another concern ,.can i mix non round up seed with my present type .I know I would have to change my m. o. for weed control. need help .

new planting alfalfa