Although you might get away without the realtors association.The license renewal cost is about $45 for a year.I was actually an investor like you but got tired of the constant realtor calling to see a property so i got my own license.

If we have a tenant that isn't working out so well (i.e. paying on-time, complaining), we don't renew.  

The original lease was month to month, no renewal clause.

I'm in a difficult situation with a tenant.  The end of the lease is 3/31 and I sent him a lease extension in February.  We then got into a heated argument over a dishwasher and now I do not want to lease to him anymo...

At the beginning of the month I reached out to my management company to see if they had a renewal plan for our current tenants (They are set to renew/move out at the start of May).

Some, you have to treat them as if they were your children and just educate them, hold their hand a little bit until they get the process down packed. and if they can't then don't renew their lease/ worst case scenario evict based on failure to follow agreed upon lease/policy of the building.

Lease renewal fees?

Their lease renews with me on June 1. 

Seems the best route if have an existing owner renew the license before the sale. 

If you can not wait till tenants move out on their own, allowing you to do electrical during vacancy, I would non renew one tenant at a time to complete the necessary work.