Replace Crankset Claris with 105
The FC-2450 uses a Octalink bottom bracket. A newer 105 crankset would be a Hollowtech II, so at the minimum you'd need a new bottom bracket. You'll also need to make sure you can position the front derailleur for the change in teeth (probably can), and probably get a new chain to account for the extra teeth.

That being said, if you want a bit of change in gearing, changing the cassette rather than the crankset is probably easier and cheaper.