Going on if it was a regular day for me, like today, I think I would do this:
The first few days I play out the same way a few times, just hanging on the PC, playing games etc., just to see if there was any shifts, anything I could make change, and also having repetitive fun.
Then I would start experimenting:
Killing people (yeah that was a jump from having fun to... having fun again I guess), 'cuz there are people I don't like and I'd relieve some stress to relieve them of blood. Hm... go see people I hardly talk to anymore, buy stuff that I would only use for one day anyway (like a replica katana... for that fun I was talking about) and other such luxuries.
Then I'd get really crazy and start introducing people into my world. I mean, I have infinite retries to find the perfect combination of words to convince someone I am eternally reliving one day. And if I managed that I'd get them to do something equally crazy as I had been doing, with me. It's always more fun to be idiotic with people.
I'd probably go through the Bill Murray suicide phase and these would the ways I'd try:
Jump out a plane
Jump in front of a train
Attempt to die in a fight
Shot in the head would be a nice one
If I had an infinite amount of day(or days) to repeat then I'd probably find loadsa other things to do. Though I'd probably try and get on a plane to America and meet people I've only talked to on msn so far. Though those flights are so long, that'd be difficult.