I had a similar problem where I needed students to be able to make as many submissions as they wanted. This was with 1.8.4.
I had a look into the workshop module and made a couple of small changes:
lines 182, 184-188 - commented out these lines to always show workshop description text; you may want to do this part too
line 254 - change '$n=0' to '$n=1'
line 46 - remove '- $CFG->maxeditingtime' from calculation
I have just looked at the 1.9 code and the fix is the same except the lines have moved up/down a little.