What are valid reasons to increase rent on tenants

[Anthane C. Richie Sr.]

I have a tenant who is currently paying $650 for a 2 bedroom 1 bath. Their lease is up in April. I noticed their fridge is a bit old and rusted. Would a good bargaining tool to lock them in for another 12 months and increase their rent at the same time by purchasing a ($300-$400) fridge. Increasing their rent by $25-$29 would have that fridge paid back in 12 months. Is this a good bargaining strategy with increasing rent.