i have a student loan denominated in US dollars. i live and work in the US.  i
am both a US citizen and a citizen of the EU. i have residences in
both countries. i pay my loans monthly with 10% interest. i would like
to limit my cost for these loans.

right now interest rates are lower in certain countries, like japan. can i take
out a new loan somewhere in japanese yen at a lower rate? or in euro's
at a similar rate to the US - but i will owe/less or more depending on
how the exchange rates fluctuate (if i believe that the us dollar is
currently undervalued and will gain stregnth, it will make my new loan
denominated in euro's cheaper, right?) where can i take out such a
loan, i have searched and searched and have been unable to find
anything but shortterm commercial loans in foreign currencies to
finance import/export.

again, i believe that the dollar will gain in stregnth vs the euro. 
by what other method besides the loan can i expolit this? should i
instead sell forward contracts on the euro? for what time period? my
loan is for 15 years, but as i understand, forward contracts are only
for up to one year. how do forward contracts work? is it like options,
where i can sell 'naked calls?' am i paid when i sell, and then i have
an obligation to buy the euro at a later date, right?

You can certainly take out a loan in a foreign currency and use the
funds to pay off the student loan.  However, your creditor will likely
want USD, so you will have to convert the currency before paying.