Possible methods for copper (II) reduction to copper (I)
There are several ways to make copper(I) oxide from copper:-


Heat it


$$\ce{4Cu + O2 -&gt;[\Delta] 2Cu2O}$$

Copper react with oxygen to produce copper(I) oxide. This reaction takes place at a temperature of over 200°C.


Heat it with nitrous or nitric  oxide


$$\ce{2Cu + N2O-&gt;[\Delta] Cu2O + N2}$$
$$\ce{4Cu + 2NO-&gt;[\Delta] 2Cu2O + N2}$$

Copper react with nitrous and nitric oxide to produce copper(I) oxide and nitrogen. Both reaction takes place at a temperature of 500-600°C.


Heat it with copper(II) oxide


$$\ce{Cu + CuO-&gt;[\Delta] Cu2O}$$

Copper react with copper oxide to produce copper(I) oxide. This reaction takes place at a temperature of 1000-1200°C.


If you made copper (II) oxide, just heat it


$$\ce{4CuO -&gt;[\Delta] 2Cu2O + O2}$$

The thermal decomposition of copper oxide to produce copper(I) oxide and oxygen. This reaction takes place at a temperature of 1026-1100°C.

Since you are doing this at home, method 2,3,4 cannot be used as it requires laboratory grade heater but method 1 can be used since it require 200°C which is achievable. 

But the best method(according to the comment) I would recommend is the Fehling's test. All you need is Fehling's solution and glucose which can be purchased from sigma-aldrich at affordable price.

$$\ce{RCHO + (2Cu^2+ + 5OH^{-})-&gt;Cu2O + RCOO^- + 3H2O}$$