1. What will you do differently to be successful this time? If you apply with the same application, you're likely to get the same result. An IM internship will not help in any way -- by the time you're applying, you'll barely have completed 2 months and the most anyone will be able to say about you is that you're an early intern.
2. Getting the time to interview can be difficult. You'll have a paid position next year. Your employer is not required, nor expected, to give you time off -- especially when you're trying to find a new job. You can certainly plan for a week or two of vacation during interview season -- but realistically, how likely are you to pack enough interviews into a 2 week period? How flexible were your interviews this year, would that have been possible?
3. The match is in March. If you've scrambled into a Categorical position, your PD will likely want to know well before then whether you're continuing or not. You could easily lose your 2nd year position, and then not match. This will be program specific -- some PD's might hold your spot until after the match. This assumes you have a 3 year position, if you only have a prelim then this isn't an issue
