If you are running a contest and the outcome is not what you expect, pleeeease do not change the rules! Changing the rules during a contest/sweepstakes may seem like the answer but if you have anyone who already entered the contest you are setting your organization up for ridicule including bad PR, and a possible lawsuit.
Your organization may be upset that the contest/sweepstakes you are running is not attracting as many people as you had hoped and the only answer to that is for YOU to work harder to get more entries. Possible ways you can do this are contacting some bloggers you know and asking them to help promote the contest through their channels. If you wrote a press release but did not follow up NOW is the time to follow up. It is never to late to follow up even though following up should be part of your original plan. Do a viral video yourself about the contest. The video does not have to be professional produced. Some of the best viral videos are from organizations that pull out their Flip and shoot.
Things you need to look at are: Do we have the contest/sweepstakes information located properly on our website so people can find it? Ask someone you know that is not that great with the computer to try to enter your contest and first see if they can then secondly ask them if it was difficult for them to enter. If they could not find the entry point move it where you will get the most attention. We know everyone hates paper these days but postcards still work. Place postcards at your business location and/or pass them out to businesses nearby so that they can distribute them. Lastly, use your social media connections like crazy!
We could go on and on about all the things you should to do and frankly all of these ideas should have been done in the first place. Just remember whatever you do changing the rules by extending the contest/sweepstakes or altering the rules is not the answer. If the contest does not work out and there is no way to fix it look at it as a learning experience and consider consulting with an agency or having a brainstorming session with your colleagues to come up with ideas on how to improve for next time. If you hired an agency to handle the contest and it was not properly done talk with the appropriate heads and see what went wrong and possibly fire them and move on.
There is no easy solution but to suck it up and learn from your mistakes and move on. If you change your contest because you think it is going to help your organization you are not helping anyone and in fact you are probably hurting yourself the most. Remember an upset entrant can spread negative talk about your organization faster then you can spread positive talk.