multi entry visa

hello, my husband has worked in china for the past 7 years, he has a multi entry visa with his job but when i visit him which is quite often his work applys for my visa but i only ever have a 1 entry visa and i would like a multi entry so i am not filling in the visa forms evry time i visit, what do i have to put on the visa form if i would want a multi entry visa, i heard you have to put the dates of when you are visiting for the whole year but i never know when i would be going? thank you so much.