No limit. Number of reasons replies might dry up - people who've been helping get distracted (by work, going on holiday etc); people reached the limit of their ability to help, you problem is too large, or too poorly specified, too many pages back to get noticed now etc etc.
Have a re-read of your posts, then see if any further clarification would help. It is OK to 'bump' your post back to the top after a day or so (by posting a reply to itwith 'bump' in the text) - but if you do, always think first if there's any other info you can provide that might help.