If i delete a psn game by accident, can i download it again?

May be...

or is there a time limit

no limit that i know of, you should be able to download it again

yes u can go to the play station store and in the top right theres 3 little pictures click vie downloads go to the one u want to download again and just hit x to redownload and no there is no time limit

No time limit, just head to the PS Store, go on your download list and re-download it.