Figuring out the next step

So, my house is rented out. 2 year lease, and the tenants are interested in purchasing, possibly after one year (but I imagine it will be 2 years.).

So - this is good. However, my cash is tied up in the house now, and I can't refinance for 18 more months without a 6 month interest penalty payment.

What I need to do is crunch the numbers to see if it is worth it to take the penalty hit in order to get my next house and flip it.

I have decided no more 2 bedroom/1Bath homes unless there is room enough to add a 3rd bedroom.