Hola Iris

Both are fine, disfruta tu vida and disfruta de tu vida - it depends on whether we use the verb disfrutar as transitive or intransitive. If we say "disfruta [algo]" that "algo" is the direct object (transitivie) and if we say "disfruta de [algo]" that "algo" is a different type of complement, not a direct object, but the meaning is really the same. 

Also, the verb disfrutar can have a slightly different meaning when used with "de" [algo]. For example here:  "Mis padres disfrutan de una buena salud.", this means that my parents have / are in good health, so it goes beyond the general meaning of "enjoying" as in having fun; it's more to do with "having something". 

Saludos