Should I apply for a position which I previously applied and had an initial interview?
Yes. The cost of an application is essentially free -- these days you don't even have to pay postage. Unless you were specifically told that you were categorically unsuitable (e.g., you had a felony conviction and the job required contact with minors) then there's no reason not to reapply.

It's more curious why the same job popped up again. Either the search failed or the candidate bailed after being hired. You might want to delicately inquire as to what happened. 

You clarified that this is for a post-doc or other temporary position. In that case, there's all the more reason to reapply. While applying should just take you about an hour of your time to brush up the CV and letter since you did everything last year -- As aparente001 notes, you may want to invest just a bit more time to figure out what the committee is looking for and hone your application a bit more.