Invest 9 quid in the wheelpro wheel building book and learn how to do it yourself.http://www.wheelpro.co.uk/wheelbuilding/book.php
TBH Those rims are cheap nasties, and if its the factory build, will be fairly feebly built as well with cheap spokes. May be worth investing some time and money in building up some better rims/spokes on to the existing hubs (or some new SLX hubs, there are some deals around ATM). Not only are you likely to end up with better/stronger/lighter wheels, you'll have learnt how to build/true your own wheels.
I build most of my own, and have for 15 years, and they usually last until either the rim wears out on the road bike, or i crash (hard) on the MTB and damage/dent them (i tend to use the lightest rims i can, slightly heavier rims will prevent your lad doing the same.)