Regarding applying for a new work permit at the border, this is what immigration says:
I have heard of one person who was not visa exempt and had a multiple entry visa who did go to the border and was granted a work permit but that was probably a mistake as the rules are clear. Still, it could be worth a try if the border is not too far away. If they don't grant it at the border, you can still mail it in and wait 66 days.http://www.cic.gc.ca/english/work/apply-who-eligible.asp#enter said:Eligibility to apply as you enter Canada
You can apply for a work permit as you enter Canada, but only if you meet the following requirements:
you are temporary resident visa exempt and
your job does not need a labour market opinion from HRSDC (some exceptions apply) or
you hold a labour market opinion from HRSDC.